Ulvenwald Amalgamation

Ulvenwald Amalgamation enters the battlefield with X +1/+1 counters on it, where X is the number of Zombies you control.
At the beginning of your next upkeep, double the amount of +1/+1 counters on Ulvenwald Amalgamation.
Creatures you control gain Indestructible and Trample as long as this creature has ten or more +1/+1 counters on it.