I tested it a couple of weeks ago...you need full imbuing (or is it eval?) for it to be effective, but if I remember correctly, at max imbuing/mysticism, it's something like +5 to all resist caps and +14 to all resists, with a 20% damage increase and -5% SSI (I think) -- and you move pretty slowly. It's a nice bonus, but comparable to what a swamp dragon provides, and unlike with the swamp dragon, you're basically rooted since you can't ride a mount while using it. Hence, I don't really see it being something to build a template around. There might be situational uses, but I think that's about it. The only thing I could come up with is with mystic/tamers in certain situations where they have to take AoE damage -- since tamers tend to run with somewhat lower resists, it could be a big boon to survivability if your pet can hold aggro on whatever it is you're fighting. But honestly, even in that situation, I think 9 times out of 10 I'd rather be able to flee.