That fight design is basically that though: a DoT race. Once you’re ahead, you just have to maintain the lead until the end. You can either run circles around the arena, not risking any more worm kills (in case you can’t get him in there, and you catch some DoT), or lurk by the rocks and let him stew in his own juices. For a challenge, one could certainly stack pools on him repeatedly, but you’re so much more vulnerable to them than he is. I do enjoy challenges like that though, but when I’m after loot before combat, I will similarly park by the rocks and go do some chores.
I’ve mentioned this elsewhere, but I think I’d like this fight mechanic quite a bit if it was scaled down to a normal/mini boss (where maybe five worm pool applications would finish the job or something), and the pool didn’t spread to fill the entire room (give it a limited range, but with a limited duration too, so if nobody eats the pool within some set time, the pool vanishes, and you have to set it up again).