Xyra, Emptiness Enslaver

At the beginning of your end step, if a player
has lost life this turn, you may return target
creature from any graveyard with an empty
counter on it. Creatures with empty counters
on them are have the creature type Eldrazi in
edition to their other types.
{c}{t} Target player loses X life, where X is the
number of creatures you control with empty
counters on them.