The special attack used by the Xala'shar overseers behaves improperly when used against the other creatures. The messaging is messed up, and it doesn't actually do anything to them when it says it does. They neither fall to the ground nor lose any spirit health (assuming the "incredible spirit which is healthy" bit in creature appraisal can be believed). I've put underscores where there are blank spaces in the messaging below.
A hulking Xala'shar overseer slams its foot into the ground as it begins to vent a thick cloud of smoke, surrounding its heavily armored frame in a choking mass of black.
Moments later, the Xala'shar overseer emits a metallic roar as the black smoke suddenly coalesces into the ghostly silhouette of a humanoid figure, which speeds towards a hulking Xala'shar overseer!
The smoky silhouette lunges forward and winds its formless body around _ with the ease of a serpent entangling its helpless prey. _'s eyes grow wide as H lets out a blood curdling scream of terror, and collapses to the ground in a shuddering mass!
Also, I had two overseers in the room. One was manipulated and facing the second, and the second was facing the first. At some point, one of them still used the special attack against me.
I should mention that this all happened in Test, but I have no reason to expect that it would work differently in Prime.
Thanks,
-Biomancer Karthor
