if you want to focus on fire, then savrog. Even she got her aw very early, she is still a decent dmgdealer compared to all the new kamis on dmm.
Some ppl may recommend Mars too. Mars is nice, but only for the moment. U can get 25% defense down with hercules special weapon. Later u will want a quick burst team anyway. Ares and Savrog both gaining burst gauge every fast, they will keep their slots in team. 10 months later when uriel and acala get their aw, u wont give a fuck about those debuffs.
Problem with fire is the weapon grid. event weapons are rare, u need to fill it with gasha weapons (mlb). which means money money.