I don't even know how to describe this.

Started the fight, skipped two turns of my Impulse hero, Vetrar cast Blizzard (dealing a massive 8 damage to my level ~11 heroes)

Then my caster hero came up and I tried to cast Haste... except the pointer was giving me the tooltip 'must be cast on one of your own units'. I then tried to cast Storm after failing to cast Haste and... it Stormed MY units with the tooltip of 'Storm' popping up for VETRAR.

In otherwords, Vetrar has possessed my mage

Next, I couldn't attack him in melee. I've had trouble attacking the wildlands bosses before, usually targeting their 'center' square worked - not this time. All three of my melee heroes couldn't attack him.

Next, Titan's Breath knocked him over, despite his supposed immunity.

Next I used a Silver Flute and it spammed +Dazed over his head about six times

Then when it wore off it spammed -Dazed about another six times

Oh and, the 'unit ready' green space highlight was underneath my caster for the entire fight.

And then just to wrap everything up in a nice bow, the game crashed after I killed him

Here's the save, you see if you can make sense of it

http://www.mediafire.com/file/6go7id7c2c8wh8t/Game 1 76.EleSav