This is a new feature of the King’s Tower in patch 1.18. It’s unlocked after completing stage 15-1.
Each tower can only be challenged by a team of heroes that are the same faction as the tower.
You can only complete 10 floors per day and the different towers are rotated on a daily basis.
There’s currently 4 different towers:
Tower of Light
Only Lightbearer heroes can be used to challenge this tower.
This shining edifice was erected millennia ago by King Anion in memory of his grandfather, King Luther, the first king of men and the first bearer of the light.
Many champions of men have attempted to reach the zenith of this inspiring monument, seeking to pay homage to the old king, yet have failed in surmounting the challenges that face them along the way.
The path to the old king’s sky tomb is treacherous and full of hidden dangers. Only the most resilient and resourceful are capable of summiting this cloud-capped trial of stone to pay their respects to King Luther.
The Brutal Citadel
Only Mauler heroes can be used to challenge this tower.
Nestled between mountainous peaks, this daunting citadel is carved directly into the rock. Its unassailable facade brandishes hard angles like weapons, seeming to challenge all who view it. Behind its walls, torch-lit arenas ring with the sounds of clashing weapons and brash taunts. A regular stream of fresh mauler warriors descend on the place, all eager to prove to themselves and the assembled clans that they are worthy of their Mauler moniker.
The World Tree
Only Wilder heroes can be used to challenge this tower.
This gargantuan tree draws Wilders of all stripes to its impossibly wide trunk. Inside, it is criss-crossed with meandering corridors, not carved but integrated into its growth pattern through ancient magics. The interior surfaces are covered with ropes of branch and vine that support the wondrous tree like a woody musculature. Those with an affinity for the forest find themselves inexplicably drawn to this behemoth, as to ascend to the canopy is to find oneself communing with the heart of the natural world itself.
The Forsaken Necropolis
Only Graveborn heroes can be used to challenge this tower.
Once a place of final rest for the dearly departed, the necropolis now houses a new ominous tenant. Long gone are the days where the dead could rest and the living honor their memory. The evil that walks these halls has warped the natural order into a twisted perversion of itself. Dread energies enshroud this accursed place, where the once peaceful silence has been supplanted by the skittering sounds of bones against cold stone.