Here's a problem having to do with the proper resolution of the stack. My friend played Decimator of the Provinces for its emerge cost by sacrificing his Hooded Hydra. In response I played Disperse targeting his Hooded Hydra. This way he wouldn't have enough mana to play his Decimator of the Provinces.
Is that how it would resolve? And if so does the Decimator of Provinces return to his hand or go to his graveyard?