I do not know if this intentional or not but in troll laboratory you can imawall any level ten creature (not the boss) and he will keep his effect (even if you decide to endiswall that creature turned wall) but you can also use a slayer's wand on those creatures and it removes the effect from the boss. this could allow any class to do 400+ damage with 1 item at level 1 twice (once if prepped and once if they find the item in the undead kennel subdungeon). further testing needs to be done on wand of binding.
if this not I think I know a solution. all you have to do is make it that the sub bosses are actually considered bosses and when the main boss is killed you can drop the max health and damage of these sub bosses to 1 (or even drop dmg to 0 as deathgaze man would still kill from the single dmg)
edit: further testing is complete and it appears that the wand of binding will do a similar effect to that of the slayer wand except an animated armor will appear and it does NOT have to be killed for the boss to be harmed.