Kill the guards on 4th floor in Highkeep until 40. 150% ZEM highly underconned. About 10 spawns on upper floor. Most still DB.
Then spectres in feerrott t --> 45.
Then Bloodgills in Loio --> 50.

The Tollbooth guards in WC will go light blue at 42 (i'm 99% sure, since they're level 30 and the qeynos guards in NK went lblue at 42 and are 30).

But until then, yeah - you can do the three NK Guards at the bridge (there's one inside the tower and two facing SK on the bridge), although you're not getting any ZEM for your efforts. Since you're a shaman and you have your pet, Paw, Lower Guk (you'll have to play around to find a good place), basically anyplace that has soloable level 30-34ish mobs.

However, this guy's suggestions are awesome:

HGs in Rathe Mtns when not too crowded. Parts of CoM are also very good. Overthere offers plenty of mobs, though little loot and is super grindy.

I so far as similair lvl sham to OP have found specs super tough. Just dinged 39 though so might head over to feerott and give em a go. oasis ones tho seem to resist to regularly to be mana efficient and hit to hard and fast to try to tank even with slow. add in that 6? second stun and Ive been pretty gg on them

Highkeep ZEM seems to be completely broken.