Activated ability

An activated ability is an ability that can be activated by paying its activation cost, which often includes mana or tapping but can have many other components. Activated abilities are usually found on permanents, but can sometimes be used on cards in other zones, such as the graveyard or a player's hand.
==Usage==
Only an object's controller (or owner, if it has no controller) can activate its activated abilities, and only when it's on the battlefield, unless the ability specifically implies otherwise. These abilities can usually be activated any time the player has priority and uses the stack, unless it says otherwise, or is a mana ability. Mana abilities can also be activated while paying a cost, and do not use the stack. Like triggered abilities, activated ones may have targets.
An activated ability of a creature that includes the tap or untap symbol ( or ) in its cost cannot be activated unless its controller has controlled it continuously since the start of their most recent turn, or the creature has haste. The same criteria applies to attacking with a creature; this rule as a whole is informally known as "summoning sickness".
Activated abilities cannot be countered by spells or abilities that counter spells, because they aren't spells. However, there are cards, such as <c>Stifle</c>, <c>Squelch</c>, and <c>Voidslime</c>, that do counter these abilities.
Most of these abilities are written in the form "[Cost]: [Effect]", with a colon to distinguish the two parts and identify it as an activated ability. Colons aren't used in Magic rules text for anything other than activated abilities, and are the one punctuation mark that has a rules meaning in the game. Many keyword abilities only have the colon in their reminder text and rules definition.
===Activate only once===
Some cards can be only activated only once per game, usually at sorcery speed. An early example was , but later examples mostly appeared in supplemental sets. Two cards appeared in a premier set: <c>Surge Engine</c> and <c>In the Trenches</c> (both in The Brothers' War).
 
This mechanic is much more common for designed-for-digital cards on Magic: The Gathering Arena because these don't have memory issues. You can hover over the card and the text will be grayed out if the ability is no longer available.
==Activation cost==
The activation cost of an ability must be paid by the player at the time of activation, and is analogous to the mana cost of a spell. It is either printed on the card, or defined by rule for some keywords. The cost most commonly includes paying mana and/or tapping the permanent with the ability (), but can can include almost anything, such as sacrificing a permanent, paying life, untapping (), or unusual actions like putting cards from a graveyard into a library. A few costs are .
Unlike spell mana costs, activation costs are very flexible in phrasing and extent, so activated abilities don't generally have additional costs, and costs in addition to mana are simply part of the activation cost of the ability. Therefore, an ability's total cost is usually equal to its activation cost. <c>Drought</c> and <c>Brutal Suppression</c> do impose additional costs through effects however. More frequently, effects may impose mana increases or decreases on activation costs, or even increases to loyalty "costs" as with <c>Carth the Lion</c>.
==Examples==
Below are examples of different activated abilities. 
Lore Broker's activated ability can be activated any time the controlling player could cast an instant, which means they must have priority to activate it. The cost includes the tap symbol , which means that because Lore Broker is a creature, the ability cannot be played if the controller has not controlled it from the beginning of their turn. (This is informally known as "summoning sickness".)
Nezumi Bone-Reader's activated ability's cost does not include the symbol, which means it can be activated even if it has summoning sickness. However, because it can only be activated when the controller could cast a sorcery, it can only be activated during the controller's main phase when they have priority and the stack is empty.
Squallmonger's ability can be activated by other players than the controller, because the card explicitly says so. The player activating the ability must still have priority in order to do so, however.
Ghost-Lit Raider has two activated abilities. The second (which has the ability word Channel) requires the controller to discard it from their hand. This implies that it can only be activated when it is in its controller's hand. The first doesn't imply anything about where the card would be, so it follows the default assumption - it must be on the battlefield for the ability to be used.
Black Lotus isn't a creature, so its ability can be activated immediately despite having in its cost. It also requires sacrificing the card, a common restriction on artifacts to make them "one-time use". It's a mana ability as well, so it could be activated any time a cost is being paid, or when its controller has priority.
==Rules==
==References==