It has been forever since I played in the Underdark... But I recall it being possible to gather a mob of beetles and blasting them with scrolls of Fireburst. Turn those beetle pincers into gold, buy more scrolls of Fireburst, and do this until you level up.
With this in mind, extended Expeditious Retreat was literally gift from the gods.
So if the above thing still works, you can could just pick whatever arcane build you want and get some few easy levels down on your belt.
Or perhaps specify what kind of arcanist you would like to play as.
Without any builds to look at, you could just glance at this Pillar of Ice thing I did... 5 years ago!
http://nwn2db.com/build/?149519 You could literally just switch the race to drow and be solid. Some things have changed since then too, for example you could take the Automatic: Still Spell feats at levels 21, 23, and 25 to be able to cast while in armor, and spend the remaining epic feats on whatever you fancy. Automatic: Quicken Spell I-III might be an interesting idea to spam Quickened regular, Empowered, and Maximized Lesser Orbs of Cold. (Blindfight is there to counter concealment.)
Lesser Orb of Cold - 9d8, 40.5~ AVG.
Empowered Lesser Orb of Cold - 9d8 * 1.5, 60~ AVG.
Maximized Lesser Orb of Cold - 9 * 8, 72.
It could be a lot of fun.
And your AC will be pretty decent with Fullplate, Tower Shield, buffs, concealment, Mirror Images, and Improved Combat Expertise.
