I like the In Nomine setting and the Supercrew rules. So, why not combine them? I think it can work.
The 3,2,1 stats can be:
The Tricks will be specific Songs, Skills or Resonances. Hero points become Essence.
If I break the game down to its essentials then you have:
One stat of 2d which basically is your “everyday” stat and defines your character as you can use it as often as you like.
One stat of 3d which is your “Hero” stat as you can only use it by spending hero points
One stat of 1d which is your “weakness” or “power up” stat.
I guess Vessel best suits the 2d stat as this stat would be used to do things on earth. Then you can choose to have your Word and Choir/Band as weak or heroic stat.
Then you have three one-use only tricks:
Change one die to a 5
Change the roll to a Result 2
Re-roll the dice
Tricks can then be Songs, Skills or other “unique” powers.
Possible add-ons for In Nomine:
Getting a Hero point at Sunrise (angels) or Midnight (demons)
Getting Hero Points with Rites (only one per day)
Spending a Hero Point before a roll to get a +1 bonus
Summoning your Superior
A Celestial can try to summon his Superior by rolling his Word Ability. For a Superior that is easy to contact he only needs an Effect 1. For a Superior that is standard to contact he needs Effect 2. And a Superior that is hard to contact only responds on an Effect 3 or even 4 for very hard. Of course the GM can give bonusses or penalties if the situation merits it. A Hero Point can be used before a roll for a +1 bonus to the result of a die.
Each player has a Dissonance track. Every time they go against their Resonance, fail a 1d-Stat roll or indulge their evil sides, they add one to this track. Each point of Dissonace makes it harder for a Celestial to succeed. Each point of Dissonance subtracts one point from the highest rolled dice.
When they have accumulated 3 points of Dissonace, they can no longer use their most powerful ability until they’ve done something humane or heroic to assuage their guilt. The GM tells the players when they can lower their Dissonace, and all the Celestials start with 0 guilt at the beginning of each session. A player can spent 10 Hero Points to remove one Dissonance.
Immedialy after a Celestial does something dissonant the player must roll 3D. If the Effect is more than 4 minus the number of Dissonance the Celestial already had, the result is a Disaster. Otherwise the result that the Celestial only gets another Dissonance.
4-1 Dissonance=3 Effect is Disaster
4-2 Dissonance=2 Effect is a Disaster
4-3 Dissonance=1 Effect is a Disaster
When a Disaster happens the Celestial falls, becomes an Outcast or is destroyed by his Superior.
Two Dissonace can be converted into one Discord. When a Celestial has Discord he doesn’t get Hero Points automatically anymore. Each time he would have received a Hero Point he needs to roll 1D. He gets the Hero point on a result of 4,5 or 6. Discord also gives the GM one of three posibilities he can hamper the player with once each session:
Change one die to a 3
Change a Result 2 into a failure
Prevent a re-roll of the dice
To show that Celestials or tough they start with Tougness 4.
Idea: Rolling 3×1 summons an Archangel and 3×6 summons Lucifer or a Demonlord.