So i noticed tht u can cheese the 2nd part of fight so hard and literally break the mechaincs by simply not freeing ur healers during enchained. Most healers can last about 30 secs- 1 minute from enchained dots.
While healers are chained gilgamesh will only auto attack thus allowing tanks to go into dps mode.
Once healer dies other healer revives them. Rinse and repeat and u probably in the process will have skipped the dragon adds, a bunch of aoes. Cuz all it should take is 2 healer enchains before limit breaking gilgamesh lol.
Also i believe that gilgamesh only enchains the healer with the higher hp. Ran it a few times and noticed only i got enchained, even when i have weakness cuz my hp is 7.5k / 6.7k or so.

Im sure ppl found this out already but i just wanted to say hey the more you know! Also it'll help ease up the bartz card grind right?