There's a trick for split pulling casters - it takes a little bit for shurikens to hit from time you throw. Throw @ max distance, quickly move behind a pillar/rock/etc. to break LOS, let them run up towards you watching in 3rd person, FD (pray) & pull last straggler.none of those are an option on pulling/FD pulling sir. I played a monk leveling up and FD pulling and wizard nukes would break FD and then boom dead so his concern is valid.Necro pets bash... Shaman pets bash... Get a Tstaff and that's a decent amount of chances to interrupt.
OP, biggest thing is to just get levels. Once you have 8+ levels on a mob it'll be rare for it to land a spell on you regardless of your gear and with a trio including 2 pets most will be interrupted anyway.
Go to Katta (which has no casters) and you'll find very weak mobs (legos) with almost no HP that give great XP. Kill any that you see in the zone, near the bank is a great spot. At 60 you'll have better resists (inherently) and more HP and casters will matter much less than they do around 50.