You can easily get Vanaduke stuck on any of the 4 fountains, making the fight trivial. That is all.
Steps:
1 Get Aggro on Vanaduke
2 Stand behind fountain
3 Pick up water
4 Dodge Vanaduke's attacks while waiting for him to charge
5 Run away and throw water when he is about to charge
6 Once Vanaduke is on the fountain, water will respawn off the fountain, making him stuck for the rest of the phase.
7 Profit
Yes, I know bugging out an already easy encounter is lame and this is why I am posting this to prevent long term abuse.
1. This seems like something you email to Three Rings to warn them about.
2. I thought you were having good intentions but just found the wrong way of going about them, then I read the last sentence and was like "cocky? what?".