So I went to fight the abomination in the first monolith. I was using the DOT earthquake build that The Curse posted. I didn’t remember that he was supposed to be invulnerable until you hit the 4 corners first so I just started quaking him from the go, while he was still in the animation.
To my surprise, I actually got him to half health before the invulnerability hit. Meaning that with a bit more damage I could have surpassed this mechanic entirely.
While I personally dislike this mechanic, it seems to me that this isn’t the intended behaviour for this fight, so this is just a heads up that this is happening.