The third strongest enemy among the Aircraft-type enemies, the Deltathor has a large difference in stats when compared to the Balthazaar. However, while it lost the capacity to heal itself, it also gained the Homing Shot attack, which deals a random amount of hits and damage, and the Mega Cannon Lv. 1 Stored Attack, which ignores the defense of the target. Despite having rather high stats, it shouldn't be much problem as long as you pay attention to Guarding your Reyvateil and keep your party healed.