i think 6 fire quanta is too much. nerfing that to 4 would make it more fun to face an immolation rush deck, since it would get a little bit trickier to get lava golem out. for example, the combination 1 photon, 1 immolation, 1 nova, 1 golem would work. and then there would be no fire left to feed a graviton fire eater.
lava golem grows each turn, and after 3 growths, it's hard to kill it (at 7hp), and has already done 32hp damage alone. this nerf would make it less probable to have done this by the match's 4th turn, and give the opponent a better chance at killing the golem while it's weak.
the downside of this is that a fireless deck with RoF could not play that card simply by sacrificing one creature.
although, i have never seen this card used in any other deck than variants of growthsplosion, and then for the purpose of getting golems out, or use deflagration. well, at the same time, i've only played around 1600 matches, so i still have a lot to see ^^