I am lvl 56...........what zones in Omens of War could I solo?
What mobs should I avoid (ie-which are casters and which summon)?

I would say you can solo in Dranik's Scar. Some of the mobs will be a bit low to you, but if you hunt over near the NC zone in or even by the Bloodfields zone in and south of there, you should be able to find mobs that are dark blue to you. They don't summon, unless maybe one or two random nameds do...but I've had luck root rotting here for faction or whatever. Just watch for them to break root a few times and you'll be fine.

DS is probably your best bet, you may be able to handle a murkglider in NC - but they hit really hard and resist snare quite often.