Popular Egotist

The sacrifice payoff and the sacrifice outlet, folded into one three-drop body. Aristocrat decks usually split those jobs across two cards: a drain-on-death effect like Blood Artist, and a separate outlet to feed the deaths. Here both live on the same creature, and the drain triggers on the act of sacrificing rather than on a creature dying, which is a subtly wider net: it fires for any permanent sacrificed to a cost, so a sacrificed enchantment counts just as much as a creature token, and it counts your other outlets' sacrifices too. The first ability is the outlet, and it does double duty: eating one of your own creatures or enchantments buys indestructibility, taps this creature, and in the same breath fires its own drain. So the fodder you feed it swings the game regardless of whether it was going to die anyway, and each activation is a two-point life swing, one drained and one gained. The indestructible-until-end-of-turn clause is a defensive escape hatch rather than an offensive one; the tap is the price, so you cannot sacrifice into indestructibility and then attack with the same creature the same turn. What makes it self-contained is that outlet and payoff never need a third card to close the loop: the body keeps converting spare permanents into steady drain for as long as you have things to eat.