I have a wraith weaver mage using 4/6 casting and it works great. Huge range and faster spells.
same here, works great!
@SouthPaw don't listen to the naysayers. It does work even with less sdi. Here's what I used to do with a 4/6 casting, low sdi suit (nothing fancy, even works with imbued gear - I did this on Siege!):
Template: 120 magery (with mageweapon), weaving, necro, spirit speak, music, disco.
Using the necro mastery I went to the rat dungeon, commanded two skeletal dragons and went to despise. Got in Wraith form and let the dragons kill stuff by themselves. All you do now is teleport around and thunderstorm lvl 1 and 2 to death.
Once lvl 3 is about to pop go find your skeletal dragons and tell them to follow you and guard you. Now you keep casting thunderstorm to get the lvl 3 spawn to target you which will automatically trigger the guarding skeletal dragons and they will one hit kill one rat mage each, cast thunderstorm again and another two mages are gone, do this over and over, cure/heal up if necessary and move on.
Lvl 4 you just send in the dragons and let them do their thing. Stand back and maybe speed things up with wildfire, thunderstorm or essence of wind - up to you.
Once the champ is up have the dragons attack him, discord him and cast animate corpse on 3 rat archer or silver serpent corpses to have 3 Liches attack the champ on top of the dragons. Keep the dragons healed, cast necro spells to further damage the champ and use WoD to finish him off when he's low enough.
A rat spawn shouldn't take longer than about 30 minutes from start to champ dead with this set up - depending on your level of experience with this template it can be completed even faster.
Good luck!