Oh I see now. Though a THM could use Fire anyway. You just would have to equip the spell. And I know I use all the elemental spells when Im THM because my strategy is Scourge -> Bio -> Blizzard -> Water -> Stone. This is because when Scourge's debuff hits all Umbral-elemental spells (Blizzard, Water, Stone and Umbral [of course]) become stronger then they were without it. The same could work for Astral elemental spells (Fire, Aero, Thunder, and Astral) Banish -> Dia -> Fire -> Aero -> Thunder. So yeah. . .