Beneficial immunity effects from abilities such as Ice Block and Divine Shield will no longer cause the Shade of Aran's explosion effect from Flame Wreath to proc when the duration has faded.
I'm sure he'll still wipe my guild without breaking a sweat -- he's what we're currently stuck on in Karazhan. Aran is the sixth boss in Karazhan (or so). Flame Wreath is an effect that puts a ring of fire around you; if you move, thus placing your character in the flames, it pretty much wipes the raid.
And another piece of bug-fixing goodness, they've fixed that ridiculously obnoxious graveyard bug in Blade's Edge Mountains. I'm sure I'll still hate the zone when I take my third Outlander through there (Mage perhaps?), but a little less, now:
All characters that die on the Northwest plateau of Blade's Edge Mountains will now be sent to the Evergrove graveyard.
Previously, if you died up in the northwest of BEM, your ghost appeared at the Sylvannar graveyard (for Alliance; I'm not sure what the Horde equivalent is). While this is geographically closer to the northwest part of the zone than Evergrove is, due to BEM's labyrinthine layout, it takes a good ten minutes to run back to your corpse from there.