Beatrix, Feared One

Latch On — {1}{b}{g}: Exile Beatrix, then return it
to the battlefield as an aura attached to target creature. Activate only as a sorcery. It becomes a creature again if it's not attached to a creature.

Enchanted creature gets +2/+2 and has fear as long
as it's a creature you control. Otherwise, it gets
-2/-2 and has "At the beginning of each upkeep put
a -1/-1 counter on this creature."

Fear