I boosted my hp to 3,000 with build going into this fight, then the enemy copied my hp. Since I had no %hp damage all I could do is hope to overflow my hp for one of the following to happen:
I live with negative hp miraculously and can swap my hp with the enemy, or the enemy sets their hp to mine and dies (after receiving damage possibly)
or I get to restart the fight with hp that isn't at 3,000
Unfortunately I died when I built my hp to over 2^64 and my hp was set back to the 3000 I entered the battle with and I was softlocked