I got advice while running Stone Vigil that was helpful, that I should Fire 3, Fire, Fire, Fire... it's proven to be good advice. Now that I'm almost at 50, I want to make sure I'm rotating right for end game.

I always start Thunder 3 and then Sleep in dungeons for groups of three or more enemies.

After that, it's Fire 3 then four Fires or so. If Firestarter kicks in with >1000MP, I Fire 3, if it kicks in at <1000MP I Blizzard 3 and Fire 3 as soon as MP tops off. If there's no Firestarter at 400 MP, I Blizzard 3, Thunder 3, and then start with Fire 3/ 4x Fire again.

I work in that Slow/Heavy during the Umbral Ice phase occasionally, and in boss fights I'll toss out Virus and Eye for Eye during the Umbral Ice phase.

Anything I'll need to tweak on that for end game?