Quad Spirit Summon

Quad Spirit Summon is a skill Luka learns near the end of Chapter 3. Luka first witnesses this skill when Heinrich borrowed his body in the Sealed Sinner's Prison to battle hordes of angels.

After Micaela leaves once she helped out Luka and Alice in the final battle with Ilias, the skill appears on the second page of ths skills list. It will summon all four spirits in a single turn, costing 10 SP to use.

This skill isn't really useful since manually summoning the spirits costs less SP and taking those four turns isn't really too hard. Also, Salamander will restore SP to full anyway, while this doesn't.