Damage is dealt either by creatures or by spells
Getting your choice of removing one creature or debuffing all creature tokens in play is a modal spell worth taking
7 Hydroid Krasis Triple The Creature Types Blue and green decks love doing two things, making mana and drawing cards, and with Hydroid Krasis, you can do both while throwing in a little life gain on top
In the command zone, he's likely to have the same problem as my mono-black Sheoldred deck
In fact, Primeval Titan has been the face behind some of the most degenerate decks in Modern, starting with the Cloudpost deck that was prevalent in the initial days of the format, to the Red-Green Valakut deck, and then the Amulet Titan deck both in its degenerate form with Summer Bloom, and the more toned down version we see today with Dryad of the Ilysian Grove and Urzas Saga
Zodiark, Umbral God Embrace the blackness and get Zodiark who is an undeniably indestructible, mass murdering threat to the game