Put the fairy on steady during boss fights, even when she switches to guard she shouldn't use her aoe heal, than you can use it instead of letting the AI deal with it, even than, its better just to place the fairy in the middle of the room so she can get everyone in range, unless they move out, but its pretty far reaching.

So far healed as scholar for haukke manor and brayflox just fine, had a little difficulty in brayflox where my fairy wasn't in range of the tank, so had to really go at it too keep him up, another thing, when your casting spells you can't move or order your fairy to do anything, the whole bar greys out, so best to place her pretty much right away or your gonna struggle if things are getting hairy, or just keybind place to something close.

Titan was a cakewalk, get the level 35 scholar quest out of the way and the aoe heal with the added shield is really helpful, on top of everything else, definitely not impossible, just a little harder until you get leeches.