Challenge Rooms
Look out for new white portals within the dungeons - these lead to Challenge Rooms!
Enter to face a variety of different challenges (which all involve smashing stuff) without dying. All your ability cooldowns are reset upon entering, so you can get right to it. Die, and you fail - no reward but you can leave the room to pick up where you left off.
Destroy all targets and a shiny reward star is all yours! Once collected, a choice of rewards will be waiting when you activate 'level up'. Included in these rewards are a new set of stat buffs, adding an extra level beyond the normal buffs.
This is just the first pass - this system will be further expanded over time with new rooms and mechanics.
Ability Mods
Ability Mods are now rewards, so if you want to fully tailor your build you'll need to complete challenges. This is the start of an exciting overhaul of the heroes!