Treeform Immune to All Stuns?!?!

in bgs, druid goes into tree form and is immune to EVERYTHING, sap, cheap shot, kidney shot, gouge, blind, EVERYTHING a rogue has. How exactly are 10 people supposed to kill someone who is immune to all? I'd imagine in 2s a druid + pally would be broken as all sin as if anyone gets low, Bubble... and tree form walk away.. do i put in a ticket about this or.. just take it up the yoohah?

***EDIT*** seems only sap and gouge (incapacitate) are not working. must have just missed every other stun >_>

Diminishing returns? Free action potion? Also druid in tree form is not considered a humanoid. Warlock banish works on them so I think tree is classified as an elemental.