Where to level? 51 mage

[Odeseus]

OOT - furies are still good xp all the way to 53, plus cash drops

EF - the IGs by Perma are still good xp all the way to 53, and 54 if you really push it. By 55 they are all pretty much LB and not worth the effort

Kaladim/BB - if you don't mind screwing up your dorf faction, killing dwarf guards is still good till 54ish

TD - Raptors are about the best xp you can find at this level, but they are pretty dangerous. You WILL pull more than 1 (probably more like 3-4) pretty often. And at 51, you can try and kite but it just isn't worth it. I'm bound on top of the fire pots so if I pull any adds, I gate, drop down and zone somewhere. Then gate back up top and resummon pet. Very annoying place for a mage, but the xp is worth it.

Lguk/SolB/Paw - there are a few places in each that are still DB at 51. Not all are mage friendly but they are pretty easy, plus you get a dungeon bonus.

Those are just the places I know of off the top of my head. All of these but the raps are pretty much shit at 55. I've been kinda stuck after that but this will at least get you to that point