Undercover Skrull

A green mana dork whose payoff is written into its identity as a shapeshifter: keep two creature cards in the graveyard and the 1/1 doubles to a 3/3 that counts as every creature type at once. That second clause is quiet but load-bearing. A creature that is all creature types slots into any tribal build as an honorary member, feeds anthem effects keyed to specific types, and satisfies lords whether they buff Goblins, Elves, or Vampires. The condition it asks for (creatures already in the yard) is the kind of graveyard fuel green and self-mill decks generate as a byproduct, so the buff often comes online without deliberate setup. What makes the design work is the ordering of its two jobs. Early, it is a two-mana accelerant that fixes any color, exactly the role a mana elf plays. Later, once the graveyard fills, it becomes a body that fits every tribal package on the board while still tapping for mana. The Skrull flavor (an infiltrator who becomes whatever it needs to be) maps cleanly onto a card that is literally every creature type once its condition is met, and onto a shapeshifter that hides among any tribe it joins.