| Step
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Image
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Details
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| 1
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Trapped Soul
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- Talk to the Trapped Soul at the entrance. She warns that the tower will flood in 15 minutes and that each cleared floor releases one of her trapped brethren.
- Choose "Let's go!!!" to start the run. She refuses to start it while enemies from the previous floor are still alive.
- Flood warnings appear at 5, 4, 3, 2 and 1 minutes left, then at 30 seconds. When the 15 minutes are over the instance closes and sends you out.
- While the instance is on cooldown, the book lets you reopen it with 1
 Voidbreaker Key.
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| 2
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Trapped MvP Soul
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- Every floor spawns 1 random trapped MvP, drawn from the full list below. There are 5 floor layouts and they repeat in the same order.
- Each run has a favoured element, announced at the start. Every boss has a 50% chance to use it, otherwise its element is random, with an element level between 1 and 4.
- Every boss is buffed based on the difficulty level: power up, relieve on and millennium shield scale with it.
- Difficulty starts at 1, goes up by 1 every 5 floors, and stops at 9.
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| 3
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Dimensional Portal
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- After the boss dies, walk to the Dimensional Portal and use it to move on. It only answers once the floor is empty.
- A short progress bar plays at the portal, then the whole party is warped to the start of the next floor.
- The portals sit at (47,28), (130,28), (219,28), (306,28) and (389,28).
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| 4
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 Chrono Coin S
 Echo Scripture S
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- Every 5th floor (5, 10, 15 and so on) spawns 2 bosses at once instead of 1.
- Using the portal on those floors pays a bonus of 2 Chrono Coin S.
- The first time you reach a 5th floor with the First time in Sunken Tower quest active, it completes there: 5 Echo Scripture S and the achievement.
- The clock keeps running through all of this, so clear the double floors fast.
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Chrono Coin S
Echo Scripture S
Rift Engine S 
Infinity Core Piece 
Sealed Evil Mind