It seems like a lot for 4 mana, even if the damage does add up quick
Giving all your creatures +1/+0 for each attacking dragon adds up fast, especially with token generators or a wide board
Azlask, the Swelling Scourge Brisela, Voice of Nightmares Emrakul, the Aeons Torn Emrakul, the Promised End Emrakul, the World Anew Hanweir, the Writhing Township Herigast, Erupting Nullkite Kozilek, Butcher of Truth Kozilek, the Broken Reality Kozilek, the Great Distortion Ulalek, Fused Atrocity Ulamog, the Ceaseless Hunger Ulamog, the Defiler Ulamog, the Infinite Gyre Zhulodok, Void Gorger
First, Progenitor Mimic is very well positioned in the format right now
Copperajah ex Ability: Bronze Body This Pokmon takes 30 less damage from attacks (after applying Weakness and Resistance)