I am not familiar with the Dryad's dispell, so if it were to work properly would it be an aoe dispell? If so, then yes Fenris would have a harder time catching her. If it's targeted then she would have to decide whether to dispell the hamstring from herself, or the dire howl off of Fenris. Would also dispell solar boon, but if I was Fenris trying to kill a Dryad with a working dispell I would save the solar boon for after the dispell, just to get that extra damage in.
On the note of Fenris, I think his ultimate is a little underpowered, and doesn't do much to make me want to put points into it. The talent for lunge can make the difference between the one that got away and the one that's dead. The dire howl talent, I'm not sure that one even works. I don't think I've seen units die from the howl before, though I can't say for sure. The dream leap talent is kinda meh, I think it would be better if it worked every time you used it, blinking you a certain distance then finishing the rest with standard dream leap travel. Could also act to extend the range of the spell, though it might be complicated to have it change the data to include the blink distance as well, not sure about it. The ultimate's talent doesn't seem worth it since the ultimate doesn't do much better with it. Maybe if the talent increased not only duration but damage as well?
That's all I can think of, for now