Hey, signed up for the forums specifically because I love ragnarok.
Welcome to the forums!
Has anyone ever polymorphed/switch bodies/potion of transformation'd into a hel dragon?
I haven't. I've tried in the past, but by the time I encountered one, I was higher level than it, so my scroll of switch bodies was ineffective. I wish that it let you choose any specific body you want in the area (excluding a few choice bodies, naturally) instead of autopicking one for you.
I've become just about every other monster and the draugr is definitely the best of the ones I've become. Fast, tons of HP, wears armor, immune to petrification (i think), etc... sadly no special abilities like a borgon vile.
With that kind of power, you really don't need special abilities. My body of choice is the swordsman, because he's plenty strong enough to get through the game, his origami ability is pretty useful, and I like having the "human" icon represent myself on the map rather than a letter, but I'm not even going to pretend that he stands up to a draugr in terms of sheer power.
Also, my technique for gaining quick levels:
1) Read a few scrolls of extinction until rangers show up... then attack them in hand to hand combat. They keep multiplying everytime you strike a ranger. Let's you get a ton of items from them to boot.
2) Wish for a dead draugr. Kill, wait til it revives, kill again, rinse wash repeat.
Those are good ideas, but risky. A botched ranger encounter can get messy, and draugr are just plain powerful, but from the sounds of things, it seems like you know what you're doing well enough to deal with all of those problems. Personally, I think the faleryn method is more reliable.
Anyone have any other tips?
I like to intentionally trigger the traps to release monsters in the borders of rooms, on the chance that it'll be something like a fire/ice dragon that carries a lot of treasure. It's obviously a dangerous thing to do, but the payoff can be amazing. It's best to have scrolls of time stop and travelling before you set it off (although those are good things to have with you anyway).
One thing that I never mentioned for newer players:
Once you make it to the ocean and river areas, you'll see manta-ray looking creatures called lorkesths. Whatever you do, you must not fight these directly. They can deal thousands of points of damage in a single turn, and are extremely tough and durable. They can't move away from water, so if you want to eat a black mushroom just after seeing some and fire-vision them to death, you can do so in total safety, and get a fair amount of exp that way. Just remember that they can take a long time to kill off.