So I've decided to add spiked pits to the Bicameral Rose fight to make it more interesting in addition to rising water. The arena has been reduced in size to make the fight more challenging. Still trying to figure out which <BOA and <CNP numbers will allow me to differentiate the fight from Omega's second phase.

EDIT: On second though, forget the water. It doesn't really do much to make the fight more interesting. Though I suppose an underwater Omega fight does sound interesting.
EDIT 2: Got rid of the spikes. Due to all the entities used just to summon Possessed Misery and Possessed Sue, perhaps adding the spikes interferes with Omega's A.I.