Chameleon Spirit

Most variable-sized creatures count something you control: your own creatures, your own swamps, the spells in your graveyard. This one points its measuring stick across the table. As it enters, you name a color, and the body becomes a tally of how many permanents of that color the opponent controls. Against a mono-color deck the read is trivial and the stats can balloon; against a careful two- or three-color board the choice is a guess made at the worst moment, since the color locks in on entry and there is no re-choosing as the game unfolds. A Spirit that arrived as a 5/5 against a flooded blue board shrinks to a 1/1 the instant those permanents leave, so its size is hostage to decisions the opponent makes after you commit. That is a strange engine to bolt onto blue, a color usually content to counter or bounce rather than to read a board and bet on it. The / carries no evasion and no protection, which means the same board it scaled against is also full of bodies that can block or kill it back. It is color-hosing disguised as a plain beater: an effect that would normally read as a sideboard card, built instead into a creature whose payoff depends entirely on the opponent having overcommitted to a single color before you ever cast it.