I was looking for a fun hybrid and took thief/druid just because it looked unconventional and I was surprised at how well it worked (at least for now) with daggers and Stalker form. The problem is that the Stalker form last 2 minutes and I have to recast it all the time. It's like having it permanent but not really. It's always on except during the interval of time between the moment it finishes and I recast it.
I know the other form(kodiak or something) lasts only 30 seconds because it's strong but... since Stalker is weaker, could the transformation be permanent until turned off (à la Diablo 2 Exp)? To counter this, it could reserve a certain amount of mana(75% less mana available or 75% loss of max mana for duration) and if a mana leech creature drains all the mana, the transformation goes off or something. I don't believe it would be too powerful because the current behavior is nearly permanent.