Whenever another creature you control dies, you get an experience counter. At the beginning of your end step, choose target creature card in your graveyard. If that card's mana value is less than or equal to the number of experience counters you have, return it to the battlefield. Otherwise, put it into your hand.

Protection from Humans Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card. {B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Flying At the beginning of each upkeep, create a 1/1 black and green Pest creature token with "When this creature dies, you gain 1 life." Pay 10 life: Untap all lands you control. Activate only once each turn.