The Carnival of Marath

Whenever a creature enters, you lose 1 life and add .

Whenever another creature enters, you gain 1 life.

Marath enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it. , Remove X +1/+1 counters from Marath: Choose one — • Put X +1/+1 counters on target creature. X can't be 0. • Marath deals X damage to any target. X can't be 0. • Create an X/X green Elemental creature token. X can't be 0.

Enchant creature Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."