Heralds of Galactus

When Heralds of Galactus enters the battlefield,
you may play a Herald card from you hand or graveyard without paying its mana cost.
When you play a Herald creature, it gets your
choice of either two +1/+1 counters, or an indestructible counter.
As long as you control two or more Herald type creatures, Galactus, the Devourer has indestructible.