ExtortExtort is a triggered ability. “Extort” means “Whenever you cast a spell, you may pay . If you do, each opponent loses 1 life and you gain life equal to the total life lost this way.”
If a permanent has multiple instances of extort, each triggers separately. (CR 702.101) (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, you may pay
. If you do, each opponent loses 1 life and you gain that much life.)
When this creature enters, pay any amount of life. Target opponent reveals that many cards from their hand. You choose one of them and
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) it.