Fungal Behemoth's power and toughness are each equal to the number of +1/+1 counters on creatures you control.

Suspend X—{X}{G}{G}. X can't be 0. (Rather than cast this card from your hand, you may pay {X}{G}{G} and exile it with X time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Whenever a time counter is removed from this card while it's exiled, you may put a +1/+1 counter on target creature.