Mashti, Spirit of Mortal Souls

Cumulative upkeep - Sacrifice another creature
(At the beginning of your upkeep, if this permanent
is on the battlefield, put an age counter on this
permanent. Then you may sacrifice another creature
for each age counter on it. If you don't, sacrifice it.)
{t}, Add an age counter to Mashti, Spirit of
Souls: Return target creature card from your
graveyard to the battlefield with a finality
counter.