Ri'Ven

Cumulative upkeep - Gain 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of your end step, put a 1/1
black Bat creature token with flying onto the battlefield for each age counter on Ri'Ven. Then sacrifice X creatures not named Ri'Ven where X
is one plus the number of age counters on Ri'Ven. If you can't, transform Ri'Ven.