The Bellerophon is a tough sell at such a high cost, but the overall value is pretty great. For 7 ER, I want to deal about 14 damage. If you only use this when there is a minion out, over 3 uses you get 18 total damage - great. This increases in value if you hit more minions or get to discard tough statuses. Each use also has the upside of being an Action, not an attack. This lets you use it even if you are stunned, ignores retaliate, and even lets you use it in Alter-Ego form. The downside is the tempo. This will likely use up your whole turn to play and doesn't kill 4+ hp minions in one use. Especially if you have to wait for minions to come out, you could have a massive delay to see your big investment pay off.

The Bellerophon is unique enough that I expect to play it in a few decks, but I wouldn't call it a staple. Against certain matchups, it may win the game by itself, so I will be on the lookout for places to sideboard this in. Maria Hill can justify any of the big helicarriers, so it will always be great with her.