trying to avert my eyes to enemies I havn't come in contact with, a couple of things that worked for me for some earlier bosses:
clinging to the wall for the sun temple worm was mentioned, I still got hit a couple of times but he wasn't vacuuming me out. I ate a spicy roll and kept the energy on high while trying to take him out. once he dissappeared off screen ( I had to do this boss/level 4x for various dumb reasons: phone calls, being ping-ponged by crystals, this bug, and 4th time the charm ) and the door remained closed with no worm to be found. I'm not sure if this is a glitch? the second time I attempted this I kept him in view by using the middle click viewer and attacking at the same time, a method that's also good for smaller pesky things like piranas, prickly dart jerks, and other things that volley off immense fire power.
for the 3 priests ( and my first attempt at sun worm ) I was using spider silk and making a quick loop around the boss which even though you only have 8 seconds of silk or something, the silk persists for a good 15-20 seconds or something. the worm could break out of it but it definitly was getting himself caught up in it and it effectivly tangled up those priests! once I saw about a dozen fish trapped in some webbing, only time I had seen something besides myself and an enemy trapped in there.
my best boss strategy is fishing, cooking and saving tho. getting all the duks lined up and then seeing what works

so far the only boss that has given me immense grief and pain was the Mithalis beast, the ones since then have been managable and I don't think it's because I'm getting to be more of a ninja ( tho that ~ is ~ a factor ) they just don't seem to have as tricky solutions as the beast? that one I had to look up what to do ( didn't know at that point I could bind and switch forms, so was getting my brain wrapped around that too ) and it still was a pain in the kark to do. afterwards I saw a youtube video of that sequence and the guy playing didn't get hit *once*