Siraya, of 40,000 Souls

Whenever a creature dies, put a soul counter on
Siraya, of 40,000 Souls.
{b}, Sacrifice Siraya, of 40,000 Souls: Create a
1/1 white and black spirit creature token with
flying; then create a 1/1 white spirit creature
token with flying for each soul counter on Siraya,
of 40,000 Souls.
{w}, remove three soul counters from Siraya, of
40,000 souls: Siraya, of 40,000 Souls gains
indestructible until end of turn.