Luna, Moon Queen

Luna, Moon Queen isn't a creature as long as
there are less than 30 -1/-1 counters on her.
Luna, Moon Queen's power and toughness are
equal to your life total.
At the beginning of each opponents end step put
a -1/-1 counter on Luna, Moon Queen for each
player that lost life this turn.
At the beginning of your end step you gain 1 life
for each -1/-1 counter on Luna, Moon Queen.