Melodis and Kassen Niaru

Melodis and Kassen come into play with X +1/+1 counters where X is equal to the amount of artifacts in play and in your graveyard. If X is 5 or more, it gains Hexproof. If X is 15 or more, it gains Indestructible.
Remove a +1/+1 counter: Proliferate. You may use this ability only once on your turn.