Hello, I just found AoA on DTRPG, and I have been reading it. I noticed that fireball gains a charge each time it is maintained and was wondering if I could use the maintain action multiple times per-turn to build up charges for it, as well as if I can spend actions to maintain the spell on the turn I cast it. For example, could I use turn one to draw reagent then cast the spell (fireball now has 1 charge) and maintain (2 charges), and then on turn two I could maintain twice (gaining two more charges, for a total of 4) and then attack with the spell.

I don't see any reason you couldn't maintain multiple times in a round, just like your example. It makes for a very large fireball, but at the expense of your actions for two turns.

EDIT: Probably best to do that with a Slow Turn on Round 1 and Fast Turn on Round 2, otherwise you're going to make yourself a target and not have AP left to dodge or parry.