FirebendingFirebending is a triggered ability. “Firebending N” means “Whenever this creature attacks, add N . Until end of combat, you don’t lose this mana as steps and phases end.”
An ability that triggers whenever a player firebends triggers whenever a firebending ability they control resolves. (CR 702.189) X, where X is Fire Lord Zuko's power. (Whenever this creature attacks, add X
. This mana lasts until end of combat.)
Whenever you
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) a spell from
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) and whenever a permanent you control enters from
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13), put a +1/+1
counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on each creature you control.