Yeah, immo decks just aren't reliable enough in an unupped environment with a 50% gravity constraint. If you can find a great build, please do.
Things we need.
PC: pulvy, deflag and steal are our options here.
CC: We have gravity pull, but that's not really the best CC. We need instakill stuff like lightning, ragepot, fire bolt, etc.
Rainbows: Having cards to utilize novas are a must, especially later in war.
Cards that have good synergy with gravity cards: voodoo doll, adrenaline, animate weapon, earthquake, discord. We need to find what we do best and make sure we have that covered.
Anti-elements cards: I'm a big fan of playing our best decks rather than trying to pack a vault of counters, but there are a few cards/decks that complete shut down other opponents that we should definately examine. I've lost a share of war duels packing holy lights and purifies so I'm not a huge fan of rolling such 1 trick ponies. Cards like wings, fire shield, reverse time are uniquely effective versus certain elements and should be explored.
Extra quanta generators: Ultimately we will lose duels, we need a stash of extra pillars/pends to make sure we can keep fielding good decks no matter what happens.