Two NPC spies attached to Team Retribution who filled and acidified the enemy's fallback trench.
The trap that decides the battle was built by two NPC team spies belonging to Team Retribution. One of them—The Porsuk Bartender Scout—carried the Chemical Alteration Spell scroll issued to NPC bartenders.
Together they dropped a Temporary Water Source Scroll into the empty Middle Trench, turned the water into acid, and covered it with an Illusion Spell. Imani reports the trench filled and the illusion holding, and when the enemy retreat blundered in, the resulting Acid Trench massacre left Baroness Victory visibly shaken.
NPC infiltrators whose improvised chemistry produced the battle's decisive massacre.