The Zenos fights (all of them) are easily one of the worst parts of the expansion. Design is garbage, just straight up craps on jobs that don't have innate sustain while being incredibly tedious for those that do. The first fight literally took me almost half an hour to complete. I was wearing full i260 left, full i270 right, and equipped with i260 Anima. Full raid gear... but thanks to the horrible design of the fight, I had no choice but to just maintain regen on myself while letting Combust slowly chip away at his absurd health pool since some dev had the bright idea to make him level 70 in a level 61/62 solo duty.