Echoes of the Past

Whenever a creature dies, put a memory counter on Echoes of the Past.
At your end step, if Echoes of the Past has two
or more memory counters, you may cast a creature
from your graveyard with flash by paying its cost
plus 2 life. Then, remove a memory counter.
At the beginning of your upkeep, if there are no creatures on the battlefield, remove all memory
counters from Echoes of the Past.