Why does White Deck of Ormendahl have Ulvenweld Hydra in it? Plus Hydra still gains +2/+2 for enemy green matches.
I have encountered a green deck which has Harness the Storm.
Multi-colored decks in events are not bugs.
Event decks should not be expected to have an identical play experience to PvP matches.
The Zendikar event had colorless cards as their “player” and could be any combination of colors. This event is no different.