she has no destruction skill so I suppose she is stuck with firebolt
I use her as a distraction really, even tho she tends to summon frost atronachs at the worst of times (in narrow corridors cutting my escape routes off)
and her destruction magic is just about any other destruction magic (craaaaap)
she has stealth skill interestingly but conjuration and spells make a ton of noise because she tends to aggro right after your first shot
if you favor stealth type gameplay I'd suggest not using casters at all as they usually make ruckus quick (shooting spells even at the enemies you are still unable to see yourself)
I just put pretty much all staves on her, which can be pretty devastating as they are able to use pretty much any (except possibly healing) and dual wield them at rather crazy dps rate
however she will prefer them over her destr magic and burn them out really fast
notable staves you can use are
fireball staves (eye of melka)
icy spear/incineration staves (expert level destruction magic)
dragon priest staves (walls of fire or storms all over the damn place, Hevnoraak's staff but they appear to be more of an eye candy than actual damage lol)
god-broken paralysis staff that stunlocks pretty much anything for 10 seconds (damage wont break the stun)
summon storm atronach staff
and sanguine rose
most of these are found within a random dungeon or upon its completion
I'd suggest to get at least the paralysis staff which is just on the start of a tiny dungeon if Im not mistaken (or a random loot)
due to npcs having deadly accurate aim she rarely misses and you may find yourself
surrounded by an army of stoned enemies
it is unbelievably broken and it can stun even giants, draugr scourge or even dremora enemies
I found mine just laying around some dungeon so I guess it was a fixed loot but I totally forgot which one it was try the
ah yes found it:
Snapleg cave
also
sanguine's rose is pretty broken, it seems to summon random dremora and most are rather devastating
problem with this staff is that looking for the quest giver is extremely troublesome
if you don't want her to waste some staves on random enemies (wolves) just take it off her and give it to her whenever it gets tough
mine uses altogether around 10 staves (even raise dead and other random stuff)
and I suggest you get
the black star if you didnt already
interestingly J'zargo will almost never use the staves (probably because he finds his skills more powerful *derp*) and will keep using his sparks/thunderbolt instead
either way I'm gonna give both some +mp items and see how it goes and whether anything changes at all