Mycor Feeding Mire

At the beginning of your upkeep, sacrifice a creature. If you can't, you lose 5 life.
{b/g}: Mycor Feeding Mire becomes an X/X green and black Insect creature with deathtouch until end of turn. Where X is the number of creatures in your graveyard.
Whenever a creature dealt combat damage by Mycor Feeding Mire dies, create two 1/1 black Insect creature tokens.