The Skullspore Nexus (PPLCI-212) [Promo Pack: The Lost Caverns of Ixalan Promos]

This spell costs less to cast, where X is the greatest power among creatures you control.
Whenever one or more nontoken creatures you control die, create a green Fungus Dinosaur creature token with base power and toughness each equal to the total power of those creatures.
{2}, : Double target creature's power until end of turn.