Gravity's vault is 40 cards. 36/40 are known from round 9:
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55k 55k 55k 55k 55k 55k 55k 55k 55s 55s 55s 55t 576 576 576 576 576 576 576 576 576 5oi 5oi 5ol 5oo 5oo 5oo 745 745 745 745 745 745 7n5 7n8 7n8 8pr
Based on their round 8 deck, which was almost identical, their other 4 cards might be from:
1x owl's eye
4x gravity pendulum
This is more than 40 cards, so they obviously converted at least one of the 5 cards above. Knowing any more than that about their vault is virtually impossible. The last winning deck I could find by gravity was a novabow, but that was I think round 6, and likely anything remaining from it was converted, or is useless by now anyway.
Our vault in pictorial form is the following:
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4vh 4vj 4vj 4vj 4vj 4vj 4vj 52o 52o 52o 52o 52o 52q 52q 52q 52q 55v 590 590 590 590 590 5f6 5f6 5og 5og 5rg 5rg 5rg 5rg 5rg 5ri 5rk 5rk 5rk 5rk 5rl 5rl 5rp 5rp 5rp 5rp 5rp 5rp 5t2 5t2 5t2 5v1 8ps
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4vj 4vj 4vj 4vj 4vj 4vj 8ps
If we lose a match, we are eliminated; therefore, having more than 6 novas is completely useless, and we should convert them to pillars/pends. It doesn't matter which we convert them to in the long run, since if we, say, convert them into 6 pillars and need more pends next time, we can just convert pillars into pends. This conversion will leave us with 14 pillars/pends, so there should be no need to convert anything else. Since we won't get any more cards except from salvage, we should not convert anything else, even if it seems completely useless. (unless we need >14 pillar/pend in a deck)
Gravity's gravity/air duo should be easily beatable with poison dial. (novabow would be an epic fail) With explosions, we can handle any nonflying weapons, with dials we stop their chargers and flying weapons, and their wings are useful only against arsenic.
If we win, and I really believe we will win vs gravity, we should salvage the air cards. We could use flying arsenics in a novabow, or use wings to possibly hard counter remaining vaults. Nightmare could be a valuable finisher, RTs prevent draws, stalling for poison and ruining flying weapon and... well you get the picture; poison dial should win it pretty easily.