I'll be honest, I've gotten completely and totally creamed by Pharaoh more than a couple times, and while I'm nowhere near the best player, it is most definitely a strong card.
That being said I would not be opposed to a decrease of one in the casting cost. I'm not sure if it needs it, but I don't think doing that would make it overpowered at all, it's definitely on the path to being overpowered, but not there or even really close yet. I think 8
is a reasonable cost for it, as is 9
.
If it does get buffed, you might see a small increase in the amount of Pharaohs used, however not a dramatic rise as most decks that use them will have plenty of quanta anyway.
All in all, either way Pharaoh is a strong card and it won't(probably) be used very differently/more often if the cost is decreased by one.
However, decreasing it by two, the ability by one, or raising the attack or hp...questionable at best very overpowered at worst. Making it cost 7
would be overpowered I say. It would be a FFQ with a more devastating creature generated and one more health
plus it's all mono until you get to devour, which could pretty easily be run off of a mark. Lowering ability cost would make it's scarab generations much easier. The cost of two does, albeit not super often, limit the production capabilities of a Pharaoh very nicely, keeping it balanced. And the boost in attk or hp would...unbalance it. It's not a heavy attacker and with 8 health it can take plenty of damage.