In a few levels you can start doing the Beza and Zeka instances. They can be requested solo, mercs are allowed and there is no lockout for new instances.
I just kill the mobs outside the tower, drop the instance and get a new one. Beza is a mix of summoned and live mobs, level 78-81. Zeka is all summoned mobs, level 80-83.
Both are requested from the Clockwork Warmarshal. For Beza simply walk up to him and say "first" and for Zeka say "disrupt".
These can be little mind numbing. But on the plus side they're always available, very easy to get to (guild hall portal), they don't respawn (making AFKs easy.. although there are rarely roaming merc spiders, zone in is safe), the vendor loot is good, and there are a couple of good rare drops (augs, a snare clickie, and a root clickie).
Back in Darkhollow I did scores and scores of Lost Notebook missions on my Necromancer. This is the new Mage version, and better in every way.
Mage specific writeup - http://eqmagetower.com/forums/viewtopic.php?f=47&t=82
Clockwork Warmarshal -
https://everquest.allakhazam.com/db/npc.html?id=26791