To make the game a real challenge you'd need to make a mode with multiclassing turned off. There are multiclass builds that dish out hundreds of damage in a single turn. Anything that is a challenge for a build like that would be unwinnable for someone playing one of the weaker pure-class builds. The power disparity in possible builds is just too huge a gap to properly balance for.
I disagree there. Finished my 1st playthrough with Bard (college of lore) + cleric (life domain) + barbarian (berserker) + rouge (thief, sometimes in act 3 i took ranger - hunter in this slot). It's possible, and no need to multiclass. If i was able to finish game with that setup, i believe you can pick anything on tactical and have a success.
