It's just occured to me that I've never trapped anything bigger than common soul gems, I know dark souls need black soul gems. Are there any monsters that need bigger than these, like greater or grand?

I bookmarked a useful little site:
http://tmxhost.com/mail/uselife.htm

hope that helps

Thanks for the link.

Well thanks to the Merlin Warlock!

Some surprises in there, right? Like bears v. cave bears, mammoth v. wispmother, etc.

I didn't know you could soul trap dragons. I thought because you asorbed the dragon's soul it couldn't be trapped.

Your original thinking is correct, you yourself absorb the soul, you don't trap it in a gem.

I don't know what to make of those dragon listings on that site, but the rest of it is pretty useful.

I believe you are able to capture the soul of a dragon in a gem. You need the soultrap spell for that. It won't work if your weapon is enchanted with the soul trap enchantment.

Never tried to soul trap a dragon, going to have to give this a try.