Celestial Spire
The Celestial Spire is a Tower Challenge centered on Act 7 (Olorun), and an extremely dangerous place.
How to enter
Talk to the Orc Guardswoman in Olorun Village to enter. In the first room you'll find a new NPC, the Tower Manager, who lets you challenge the Tower.
Don't forget to pick up the quest from the Tower Manager NPC before attempting the tower!
You can attempt the Celestial Spire 3 times per day by default. Using a Celestial Spire Entry Ticket once a day grants 3 additional attempts.
What is the Celestial Spire?
On each floor around Olorun's Village you face a series of buffed-up monsters and a unique boss. Conquering the final floor grants you an exclusive tower medal, which you can redeem for Celestial Spire rewards that help you progress further.
Chests
While climbing the tower you can win these chests. Click a chest to see everything it can contain.
A random box obtained from the tower — crafting materials and resources.
The top-tier tower reward, for only the worthiest climbers.
Production Spire Items
The Production Spire Items NPC in Olorun Village lets you exchange your tower currencies for the rewards below. Select an item to see the materials it needs, just like in-game; double-click (or click its name) for full details.
Coin exchange
In Olorun Village there is an NPC where you can exchange your 
Infinity Coins and 
Corrupted Spire Coins.