Hi! The Pagoda dungeon awards experience based on the lowest level wizard that entered, so if your balance wizard enters, the maximum tier you can get into is tier 3.
Difficulty (and exp reward) are in tiers. Tier 1 is level 1-19 and awards 779 experience. Tier 2 is level 20-39 and awards 4,650 experience. Tier 3 is level 40-59 and awards 14,730 experience. Tier 4 is level 60-79 and awards 47,620 experience. Tier 5 is level 80-100 and awards 50,090 experience.