Well it sounds like you have 3 classes so far:
1. Rogue
2. Mage
3. Battlemage.
That leaves you with 1 more 2nd tier class and your final 3rd tier class.
http://www.gamebanshee.com/dungeonlords/classes.php
Because you already have your 1st second tier class in the Arcane grouping (i.e. your Battlemage class) - you will not be able to quest for the Shugenja class (nor the Sorcerer).
You can however quest for any of the 2nd tier Rogue based classes:Hunter, Trickster, Budoka.
IF you have a female character then you also have the option of either the Valkyrie or the Enchantress for your last 2nd tier class.
Of course IF you choose your final 2nd tier class, then be prepared to select either that 3rd tier class above it (i.e. the NinjaLord is the 3rd tier class for the Budoka).. OR the Warlock (based on your Battlemage selection),
..Or the WarWitch (for either the Valkyrie or the Enchantress), assuming you have that opportunity.
..OR the Shadowlord (which is a "freebie" for all who have the CE version).
http://www.gamebanshee.com/dungeonlo...shadowlord.php