Path of Idle Sanctum tower: room layout, costs and the floor curve
You do not have to clear a floor to advance it. Each floor generates 13 rooms, twelve Audience Chambers and one Throne Hall, and beating the Throne Hall boss moves you up. If you only want height, you can go straight for the Throne Hall on every floor and skip the other twelve.
That single rule changes the cost of a climb from 15 Resonance Crystals per floor to 3.
Two different things are called Sanctum in English. This guide is about the tower adventure mode, which opens after you clear chapter 5, Desolate Battlefield. The town building of the same name is where you merge chests, and it is covered in market and Sanctum.
The floor layout
Four rows of three Audience Chambers, then one Throne Hall on the fifth row.
| Room | Enemy groups | Cost |
|---|---|---|
| Audience Chamber | 4 | 1 Resonance Crystal |
| Throne Hall | 1 boss group | 3 Resonance Crystals |
Every generated room also picks up one random affix from that floor’s affix level range, and a random chapter theme from the first ten. So the same floor is not the same fight twice, and a room that looks impossible may simply have rolled a bad affix for your team.
Audience Chambers drop equipment chests, gold, blood and souls. The Throne Hall drops all of those plus Soul Shards and a Set Chest. That Set Chest is the reason to clear Throne Halls even at floors you have already passed: it is one of the few repeatable set piece sources in the game.
Soul Shards are used to Infuse a class, which applies to every Godsworn of that class rather than one hero.
The floor curve
The enemy level climbs slowly and the attribute level climbs faster. From floor 7 onward the attribute level runs ahead of the enemy level, and by floor 100 it is 120 against level 100 enemies.
| Floor | Enemy level | Attribute level | Room affix level | Boss Soul Shards |
|---|---|---|---|---|
| 1 | 20 | 20 | 2 | 5 |
| 20 | 27 | 30 | 3 | 7 |
| 40 | 40 | 47 | 4 to 5 | 9 |
| 60 | 60 | 70 | 6 | 13 |
| 80 | 80 | 95 | 7 to 8 | 17 |
| 100 | 100 | 120 | 8 to 9 | 23 |
Attribute level matters because crit, dodge and defense all resolve against a level threshold. A floor whose attribute level is 20 higher than its enemy level is a floor where those defensive stats work worse than the enemy level suggests. If a floor stops you and the enemies do not look overleveled, this is usually why. The attributes guide covers the formula.
Clearing all 100 Throne Halls pays 1,200 Soul Shards in total. After floor 100 the tower continues as an endless challenge.
What a climb costs
Resonance Crystals come from the campaign at a base 0.10% to 0.15% per roll, from chapter 5 onward, and that rate never changes. There is no chapter that farms crystals faster.
Going from floor 1 to floor 100 through Throne Halls alone costs 300 crystals. Clearing every room on the way costs 1,500. Since the drop rate is flat and modest, the choice between those two numbers is the main decision in this mode.
A reasonable pattern: push Throne Halls until a floor stops you, then farm Audience Chambers on the floors below it for chests while your gear catches up. The chambers are 4 enemy groups against the Throne Hall’s single boss group, so they suit a clear speed team while the Throne Hall suits a sustained damage team, the same split described in team composition.
If a floor will not go
Check the room’s affix first. Every room rolls one random affix from the floor’s range, so two rooms on the same floor are not the same fight, and a Throne Hall that reads as impossible may have rolled badly against your team’s weakness.
Then check the attribute level rather than the enemy level, using the table above. Then work the standard list in boss walls, because a Throne Hall is a boss fight with the same shape as a chapter boss: one enemy group, one long exchange.