Extort...

[RDJDenley]

Can someone please explain how extort in as many circumstances as possible?

I.e. If you have a board of 5 creatures, each of who have extort, do you pay 5 B/W to make opponents lose 5 health? / if your single creature has extort 3 times, do you pay 3  mana to make opponents lose 3 life and you gain all life lost?

I man probably overthinking it, but I'm struggling to conclude to an answer here haha!

[InfinitiveDivinity]

You have to pay to activate each instance of extort once it is triggered.

[Kaylesh]

702.100a: Extort is a triggered ability. "Extort" means "Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain life equal to the total life lost this way."

Multiple instances trigger independently (b)

In other words: you can choose to pay for each time extort is named on a card. For each mana you pay, your opponents lose one life, and you gain that life, up to the number of times you got "extort" on a card, for each spell you play.