A newbie and a question: Damage while running?

[PavlovianCat]

Hey, new player here trying things out in SP for the first time (relatively), but something happened that I really have no explanation for, and I wasn't even sure what to search for to get an answer.

So here's what happened: I was playing MA R'lyeh with the newest version of CBM and an awake Void Lord pretender who was clearing out some underwater independents by himself. This was pretty early on so he wasn't wearing any equipment. I put him in the back row set to cast Body Ethereal, Ironskin, Quickness, and Personal Luck in that order. He was up against a handfull of Triton Troopers and a Shark Knight, who routed after about 3 turns fighting him.

Here's what I don't understand: While fighting the Tritons, he only took about 10 damage overall, but when he started chasing them after they routed, he started taking 10 damage a turn. Nobody was hitting him, they where too busy running, but every time he moved he was down about another 10 health. By the time the tritons had all fled off the map, he had picked up 4 afflictions.

Now he had beaten about 3 other similar provinces right before this, using the same strategy, and didn't have a single affliction to show for it. Can anyone tell me what was killing my Void Lord?