<PAGE>

         The security represented by this certificate was originally issued
         on January 27, 2000, and has not been registered under the Securities
         Act of 1933, as amended (the "Act"), and may not be transferred, sold
         or pledged without registration under the Act, unless otherwise exempt
         from such registration requirements.

                                   L90, INC.

                                 STOCK PURCHASE WARRANT
                                 ----------------------


Date of Issuance:  January 27, 2000                       Certificate No. W-WB1


          FOR VALUE RECEIVED, L90, INC., a Delaware corporation (the "Company"),
hereby grants to Entertaindom, Inc. or its permitted registered assigns (the
"Registered Holder") the right to purchase from the Company 50,000 shares of
Common Stock, at a price per share of $15.00 (as adjusted from time to time in
accordance herewith, the "Exercise Price").  Certain capitalized terms used
herein are defined in Section 3 hereof.  The amount and kind of securities
obtainable pursuant to the rights granted hereunder and the purchase price for
such securities are subject to adjustment pursuant to the provisions contained
in this Warrant.

          This Warrant is subject to the following provisions:

          Section 1.  Exercise of Warrant.
                      -------------------

          1A.     Exercise Period.  The Registered Holder may exercise, in whole
                  ---------------
or in part (but not as to a fractional share of Common Stock), the purchase
rights represented by this Warrant at any time and from time to time after
January 29, 2001 to and including February 5, 2001 (the "Exercise Period").  No
exercise of the purchase rights represented by this Warrant may be made by the
Registered Holder at any time prior to the Exercise Period or at any time after
the expiration of this Warrant.  This Warrant shall expire at 5:00 p.m. (pacific
standard time) on February 5, 2001.

          1B.     Exercise Procedure.
                  ------------------

          (i) This Warrant shall be deemed to have been exercised when the
Company has received all of the following items (the "Exercise Time"):

              (a)  a completed Exercise Agreement, as described in paragraph 1C
     below, executed by the Person exercising all or part of the purchase rights
     represented by this Warrant (the "Purchaser");

              (b)  this Warrant;



                                       1
<PAGE>

              (c) if this Warrant is not registered in the name of the
     Purchaser, an Assignment or Assignments in the form set forth in Exhibit II
                                                                      ----------
     hereto evidencing the assignment of this Warrant to the Purchaser, in which
     case the Registered Holder shall have complied with the provisions set
     forth in Section 6 hereof; and

              (d) either (1) a check payable to the Company in an amount equal
     to the product of the Exercise Price multiplied by the number of shares of
     Common Stock being purchased upon such exercise (the "Aggregate Exercise
     Price"), or (2) a written notice to the Company that the Purchaser is
     exercising the Warrant by authorizing the Company to withhold from issuance
     a number of shares of Common Stock issuable upon such exercise of the
     Warrant which when multiplied by the Market Price of the Common Stock is
     equal to the Aggregate Exercise Price (and such withheld shares shall no
     longer be issuable under this Warrant).

         (ii) Certificates for shares of Common Stock purchased upon exercise
of this Warrant shall be delivered by the Company to the Purchaser within ten
business days after the date of the Exercise Time.  Unless this Warrant has
expired or all of the purchase rights represented hereby have been exercised,
the Company shall prepare a new Warrant, substantially identical hereto,
representing the rights formerly represented by this Warrant which have not
expired or been exercised and shall, within such ten day period, deliver such
new Warrant to the Person designated for delivery in the Exercise Agreement.

         (iii)  The Common Stock issuable upon the exercise of this Warrant
shall be deemed to have been issued to the Purchaser at the Exercise Time, and
the Purchaser shall be deemed for all purposes to have become the record holder
of such Common Stock at the Exercise Time.

         (iv) The issuance of certificates for shares of Common Stock upon
exercise of this Warrant shall be made without charge to the Purchaser for any
issuance tax in respect thereof or other cost incurred by the Company in
connection with such exercise and the related issuance of shares of Common
Stock.  Each share of Common Stock issuable upon exercise of this Warrant shall,
upon payment of the Exercise Price therefor, be fully paid and nonassessable and
free from all liens and charges with respect to the issuance thereof.

         (v) The Company shall not close its books against the transfer of this
Warrant or of any share of Common Stock issued or issuable upon the exercise of
this Warrant in any manner which interferes with the timely exercise of this
Warrant.

         (vi) The Company shall at all times reserve and keep available out of
its authorized but unissued shares of Common Stock solely for the purpose of
issuance upon the exercise of the Warrant, such number of shares of Common Stock
issuable upon the exercise of the Warrant.

                                       2
<PAGE>

          1C.  Exercise Agreement.  Upon any exercise of this Warrant, the
               ------------------
Exercise Agreement shall be substantially in the form set forth in Exhibit I
                                                                   ---------
hereto, except that if the shares of Common Stock are not to be issued in the
name of the Person in whose name this Warrant is registered, the Exercise
Agreement shall also state the name of the Person to whom the certificates for
the shares of Common Stock are to be issued, and if the number of shares of
Common Stock to be issued does not include all the shares of Common Stock
purchasable hereunder, it shall also state the name of the Person to whom a new
Warrant for the unexercised portion of the rights hereunder is to be delivered.
Such Exercise Agreement shall be dated the actual date of execution thereof.

          1D.  Fractional Shares.  If a fractional share of Common Stock would,
               -----------------
but for the provisions of paragraph 1A, be issuable upon exercise of the rights
represented by this Warrant, the Company shall, within ten business days after
the date of the Exercise Time, deliver to the Purchaser a check payable to the
Purchaser in lieu of such fractional share in an amount equal to the difference
between the Market Price of such fractional share as of the Exercise Time and
the Exercise Price of such fractional share.

          Section 2.  Dilution Protection.
                      -------------------

          2A.  Record Date.  If the Company takes a record of the holders of
               -----------
Common Stock for the purpose of entitling them (i) to receive a dividend or
other distribution payable in Common Stock, options or in convertible securities
or (ii) to subscribe for or purchase Common Stock, options or convertible
securities, then such record date shall be deemed to be the date of the issue or
sale of the shares of Common Stock deemed to have been issued or sold upon the
declaration of such dividend or the making of such other distribution or the
date of the granting of such right of subscription or purchase, as the case may
be.

          2B.  Subdivision or Combination of Common Stock.  If the Company at
               ------------------------------------------
any time subdivides (by any stock split, stock dividend, recapitalization or
otherwise) one or more classes of its outstanding shares of Common Stock into a
greater number of shares, the Exercise Price in effect immediately prior to such
subdivision shall be proportionately reduced, and if the Company at any time
combines (by reverse stock split or otherwise) one or more classes of its
outstanding shares of Common Stock into a smaller number of shares, the Exercise
Price in effect immediately prior to such combination shall be proportionately
increased.

          2C.  Reorganization, Reclassification, Consolidation, Merger or Sale.
               ---------------------------------------------------------------
Any recapitalization, reorganization, reclassification, consolidation, merger,
sale of all or substantially all of the Company's assets or other transaction,
in each case which is effected in such a way that the holders of Common Stock
are entitled to receive (either directly or upon subsequent liquidation) stock,
securities or assets with respect to or in exchange for Common Stock is referred
to herein as "Organic Change."  Prior to the consummation of any Organic Change,
the Company shall make appropriate provision to insure that the Registered
Holders of the Warrant shall thereafter have the right to acquire and receive,
in lieu of or addition to (as the case may be) the shares of Common Stock
immediately theretofore acquirable and receivable upon the exercise of such
holder's Warrant,

                                       3
<PAGE>

such shares of stock, securities or assets as may be issued or payable with
respect to or in exchange for the number of shares of Common Stock immediately
theretofore acquirable and receivable upon exercise of such holder's Warrant had
such Organic Change not taken place.

          2D.  Notices.
               -------

          (i) The Company shall give written notice to the Registered Holders at
least 20 days prior to the date on which the Company closes its books or takes a
record (A) with respect to any dividend or distribution upon the Common Stock or
(B) for determining rights to vote with respect to any Organic Change,
dissolution or liquidation.

          (ii) The Company shall give written notice to the Registered Holders
at least 20 days prior to the date on which any Organic Change, dissolution or
liquidation shall take place.

          Section 3.  Definitions.  The following terms have meanings set forth
                      -----------
below:

          "Affiliate" shall have the meaning set forth in Rule 405, promulgated
           ---------
under the Securities Act of 1933, as amended.

          "Common Stock" means the Company's Common Stock, par value $.001 per
           ------------
share.

          "Market Price" means as to any security the average of the closing
           ------------
prices of such security's sales on the principal domestic securities exchange on
which such security may at the time be listed, or, if there have been no sales
on any such exchange on any day, the average of the highest bid and lowest asked
prices on such exchanges at the end of such day, or, if on any day such security
is not so listed, the average of the representative bid and asked prices quoted
in the NASDAQ System as of 4:00 P.M., New York time, on such day, or, if on any
day such security is not quoted in the NASDAQ System, the average of the highest
bid and lowest asked prices on such day in the domestic over-the-counter market
as reported by the National Quotation Bureau, Incorporated, or any similar
successor organization, in each such case averaged over a period of 21 days
consisting of the day as of which "Market Price" is being determined and the 20
consecutive business days prior to such day; provided that if such security is
listed on any domestic securities exchange the term "business days" as used in
this sentence means business days on which such exchange is open for trading.
If at any time such security is not listed on any domestic securities exchange
or quoted in the NASDAQ System or the domestic over-the-counter market, the
"Market Price" shall be the fair value thereof determined jointly by the Company
and the Registered Holders of Warrants representing a majority of the Common
Stock purchasable upon exercise of all of the Warrants then outstanding;
provided that if such parties are unable to reach agreement within a reasonable
period of time, such fair value shall be determined by an appraiser jointly
selected by the Company and the Registered Holders of Warrants representing a
majority of the Common Stock purchasable upon exercise of all of the Warrants
then outstanding.  The determination of such appraiser shall be final and
binding on the Company and the Registered Holders of all of the Warrants then
outstanding, and the fees and expenses of such appraiser shall be paid by the
Company.

                                       4
<PAGE>

         "Person" means an individual, a partnership, a joint venture, a
          ------
corporation, a limited liability company, a trust, an unincorporated
organization and a government or any department or agency thereof.

         Section 5  No Voting Rights; Limitations of Liability.  This Warrant
                     ------------------------------------------
shall not entitle the holder hereof to any voting rights or other rights as a
stockholder of the Company.  No provision hereof, in the absence of affirmative
action by the Registered Holder to purchase Common Stock, and no enumeration
herein of the rights or privileges of the Registered Holder shall give rise to
any liability of such holder for the Exercise Price of Common Stock acquirable
by exercise hereof or as a stockholder of the Company.

         Section 6  Transferability of Warrant.  Except for a transfer or
                     --------------------------
assignment of this Warrant, in whole or in part, by the Registered Holder to an
Affiliate of such Registered Holder, neither this Warrant nor any rights
hereunder are transferable.  In connection with any permitted transfer
hereunder, such Registered Holder shall surrender this Warrant with a properly
executed Assignment (in the form of Exhibit II hereof) at the principal office
                                    ----------
of the Company.

         Section 7  Replacement.  Upon receipt of evidence reasonably
                    -----------
satisfactory to the Company (an affidavit of the Registered Holder shall be
satisfactory) of the ownership and the loss, theft, destruction or mutilation of
any certificate evidencing this Warrant, and in the case of any such loss, theft
or destruction, upon receipt of indemnity reasonably satisfactory to the Company
(provided that if the holder is a financial institution or other institutional
investor its own agreement shall be satisfactory), or, in the case of any such
mutilation upon surrender of such certificate, the Company shall (at its
expense) execute and deliver in lieu of such certificate a new certificate of
like kind representing the same rights represented by such lost, stolen,
destroyed or mutilated certificate and dated the date of such lost, stolen,
destroyed or mutilated certificate.

         Section 9  Notices.  Except as otherwise expressly provided herein,
                    -------
all notices referred to in this Warrant shall be in writing and shall be
delivered personally, sent by reputable overnight courier service (charges
prepaid) or sent by registered or certified mail, return receipt requested,
postage prepaid and shall be deemed to have been given when so delivered, sent
or deposited in the U.S. Mail (i) to the Company, at its principal executive
offices and (ii) to the Registered Holder of this Warrant, at such holder's
address as it appears in the records of the Company (unless otherwise indicated
by any such holder).

         Section 10.  Amendment and Waiver.  Except as otherwise provided
                      --------------------
herein, the provisions of the Warrant may be amended and the Company may take
any action herein prohibited, or omit to perform any act herein required to be
performed by it, only if the Company has obtained the written consent of the
Registered Holders of Warrants representing a majority of the shares of Common
Stock purchasable upon exercise of all of the Warrants then outstanding.

         Section 11.  Descriptive Headings; Governing Law.  The descriptive
                      -----------------------------------
headings of the several Sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant.  The corporation
laws of the State of Delaware shall govern all

                                       5
<PAGE>

issues concerning the relative rights of the Company and its stockholders. All
other questions concerning the construction, validity, enforcement and
interpretation of this Warrant shall be governed by the internal law of the
State of Delaware, without giving effect to any choice of law or conflict of law
provision or rule (whether of the State of Delaware or any other jurisdictions)
that would cause the application of the laws of any jurisdictions other than the
State of Delaware.


                                 *      *      *      *

                                       6
<PAGE>

          IN WITNESS WHEREOF, the Company has caused this Warrant to be signed
and attested by its duly authorized officers under its corporate seal and to be
dated the Date of Issuance hereof.


                                L90, INC.


                                By : /s/ Tom Sebastian
                                    ----------------------------------
                                     Name:  Tom Sebastian
                                     Title: CFO



Attest:


By: /s/ Lucrezia Bickerton
   ---------------------------
    Name:  Lucrezia Bickerton
    Title: Assistant Secretary

                                       7
<PAGE>

                                                                       EXHIBIT I

                                 EXERCISE AGREEMENT
                                 ------------------


To:                                     Dated:


          The undersigned, pursuant to the provisions set forth in the attached
Warrant (Certificate No. W-____), hereby agrees to subscribe for the purchase of
______ shares of the Common Stock covered by such Warrant and makes payment
herewith in full therefor at the price per share provided by such Warrant.

Manner of Payment:                   Cash/Check
                       ----------

                                     Cashless Exercise
                       -----------



                                Signature:
                                          ---------------------

                                  Address:
                                          ----------------------
                                          ----------------------
                                          ----------------------


<PAGE>

                                                            EXHIBIT II

                                 ASSIGNMENT
                                 ----------

          FOR VALUE RECEIVED, _____________________________ hereby sells,
assigns and transfers all of the rights of the undersigned under the attached
Warrant (Certificate No. W-_____) with respect to the number of shares of the
Common Stock covered thereby set forth below, unto:

Names of Assignee          Address                   No. of Shares
-----------------          -------                   -------------


Name of Assignor
----------------


Dated:
      ----------------------


Assignor:
         -------------------
          Name:


Assignee:
         -------------------
          Name:


Witness:
        --------------------
          Name: