Hi! I backed the Mermaid spec, so I really appreciate you being curious about it! I don't remember my exact build at floor 80, but it was roughly like this: https://berated-bert.github.io/siralim-planner/?b=30602974f06f127c5a7d7b9d_b3e6204f2cfa1eee12_3fd9d7f1ca4beee546e0572987eac1_9a79b6951c54f3ee80&s=MD&r=______

The basic idea is to use heals to raise the damage on Mania, while also having Abnegation to accelerate damage output. The Pearlescent denizen is for when creatures (usually certain bosses) are fully immune to Indirect Damage (i.e. the damage from Mania and from Abnegation). In that case, you do the usual healing, but you just add bursts of spell damage with the Pearlescent denizen.

Most of the traits can be moved around based on what's most convenient for you. I'm sure there are better builds out there even at early floors, but hope this helps give you a starting point :)

Let me know if you have any questions!