Playing a mage solo is pretty cheesy too. Not as cheesy as a kensai-mage, but cheesy enough that most of the game feels too easy. Sure, you'll struggle to survive in the early parts of the game, but once you obtain the Staff of the Archmagi, it's all downhill from there. Supported by three skeletal chieftains, an elder elemental, and god knows what else I can summon, the game becomes too easy (until you start playing Throne of Bhaal, with monsters that have natural True Sight).