Sky Guardian

Reach
Possessed (When a possessed creature blocks or
becomes blocked, that creature exiles it. Return it to
the battlefield as an enchantment attached to the
creature that exiled it. This card loses all abilities
except haunt.)
Haunt 4 (A creature with haunt has -X/-X where
X is its cumulative haunt value. A creature's
toughness cannot be reduced to 0 by haunt.)