They just seem like such incredible ways to take over the game
(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
Tenacious Underdog For a while, Tenacious Underdog has been one of the best 2-drops for black decks to run in Constructed formats because it has a reasonably substantial body that threatens opponents for massive damage very early in the game and its blitz ability can be used from the graveyard
And, If you have an unlimited mana combo, just win the game with a single elf attack
Theyre also pretty much always going to be good thanks to the incredible mix of low-cost, hard-to-kill creatures, card advantage and general buffers
For a mechanic to be keyworded, it needs to be able to have the same action every single time you see it on a card