The damage type for Unda Arcanus Spiritus was changed for arcane to heat.. which is odd.. The real bug, though, is that Unda is not respecting the damage type adjustment of ascension class when other prestige and AA abilities do.
My Unda is doing magic damage with etherealist, or cold when I use Frigid Gift, so it's working fine for me.
Its working fine for me as Etherealist. (1513912547)[Thu Dec 21 19:15:47 2017] YOUR Unda Arcanus Spiritus hits Karnah of the Source for a critical of 7420498045 magic damage.
My coercer is set etherealist.. and unda is reading heat damage in the tool tip. All my other arts chance the damage type in the tooltip. I admit, I haven't checked parses on her recently, because I've been soloing. Only get Pugs late at night when there aren't better options for them to take 'cause nobody wants a coercer for heroics
