I was wondering why Phainon was doing so little damage and then I remembered that this boss has the AS Mirage DMG Reduction.
Which didn't matter in the end, I swapped RMC for Tribbie and the damage went up by a lot, what a weird boss honestly, who were they shilling with this boss? Firefly gets destroyed by her ult uptime, Quantum was a joke at the time, the only other character I could think is Yunlisnack (which should also get stomped by the mirage shield).
Were they unironically shilling Lingsha with this?