Additional cost

An additional cost is a cost listed in a spell’s rules text, or applied to a spell or ability from another effect, that its controller must pay at the same time that player pays the spell's mana cost or the ability's activation cost. A cost is an additional cost only if it's phrased using the word "additional."
==Functionality==
Additional costs may be mandatory or optional. Mandatory costs sometimes help determine part of the spell's effect for instance, a discarded card's properties may affect the power level of the spell. Optional costs often increase the power level or utility of the spell. Additional costs can include mana (but this does not make them part of the spell's mana cost) or other actions. They are usually part of the spell's own design, not applied by external effects, in contrast to miscellaneous cost increases.
Additional costs are added to a spell's mana cost, or alternative cost if one is used, as part of determining its total cost. A spell may have multiple additional costs, which are all added cumulatively. Miscellaneous cost increases and decreases may apply as well. Mandatory additional costs must still be paid even if the spell is cast "without paying its mana cost" (a form of alternative cost); optional additional costs may also be paid if desired in this case, even if those costs include mana.
==Rules==
==Additional cost keywords==
This is a list of additional costs that exist as keywords.
*Forage
*Spree
Keywords that use linked abilities to achieve a wide variety of effects:
*Bargain
*Kicker
*Multikicker
*Collect evidence
Keywords that increase the spell's power if an additional cost is paid:
*Casualty
*Conspire
*Entwine
*Escalate
*Offspring
*Replicate
*Splice
*Squad
Keywords that increase the spell's utility if an additional cost is paid:
*Buyback
*Jump-start
*Offering
*Retrace
*Escape