The Cap allowed you to remove three cards from your opponents deck and the Mask allowed you to give your opponent a new hand, all land, no land, all things too expensive for them to cast, its your call
While it's likely a bad fit for your K'rrik, Son of Yawgmoth storm deck and other black decks that aren't running many creatures, Contamination is perfect for commanders like Nath of the Gilt-Leaf that can play green mana dorks and reliably produce creatures to sacrifice to keep it around
Cards with the ability word "descend N" have abilities that care if you have at least N permanent cards in your graveyard
I feel okay about the decks, as Final Fantasy is doing nicely in basically every arena and the collectors are still going wild, but the Dragonscales sting
Still, the late-game payoff is certainly there