(It's not a creature.) If an ability triggers whenever an opponent loses life and its effect causes you to gain life, such as the ability of Exquisite Blood, this will loop until either you win the game or a player takes an action to break the loop
Heres what I have learned
This is a fantastic combo
I got to test out Pocket at a preview event this summer, and even with unlimited Poke Gold (I was ripping ten packs at a time for hours, it was glorious) I didnt even get close to finishing a full master set
And the most famous Charizard trading card is the first edition holographic from 1999, as it has only 2,627 certified copies
Instant-Speed removal spells like Swords to Plowshares are pretty boring to me and they're usually the first thing I cut, but being able to solve a problem that could end the game before you can untap and O-ring the threat can be the difference between life and death