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Research · Defense
Deep Cisterns
Water and grain enough to outlast the besiegers' patience — raises troop defense.
- Entity ID
deep_cisterns- Branch
- Defense
- Stat buffed
defense— Defense- Bonus per level
- +1.2%
- Maximum level
- 6
- Bonus at maximum level
- +7.2%
- Power per level
- 102
- Power at maximum level
- 612
- Base study time
- 55 seconds
- Study time at maximum level
- 13m 3s
- Prerequisites
- Moat Works at level 5, Counter-Siege at level 5
Cost, time and bonus at every level
Deep Cisterns runs to level 6, adding +1.2% to defense and 102 power each time. Studying it out costs the four soft resources — the same amount of each — and takes 13m 3s for the final level alone. Gems are only ever the optional instant finish; the study itself is bought with what your fields already make.
| Level | Total defense | Power | Study time | Each resource | Gems to finish instantly |
|---|---|---|---|---|---|
| 1 | +1.2% | 102 | 3m 31s | 12,000 | 4 |
| 2 | +2.4% | 204 | 4m 34s | 15,600 | 5 |
| 3 | +3.6% | 306 | 5m 56s | 20,280 | 6 |
| 4 | +4.8% | 408 | 7m 43s | 26,364 | 8 |
| 5 | +6% | 510 | 10m 2s | 34,273 | 11 |
| 6 | +7.2% | 612 | 13m 3s | 44,555 | 14 |
Taken from nothing to level 6 that is 44m 49s of raw study and 153,072 of each of food, wood, stone and iron — 612,288 resources in total.
Where it sits in the tree
Deep Cisterns belongs to the Defense branch — the walls line — what an attacker has to get through before they reach your granary. It stays locked until Moat Works reaches level 5 and Counter-Siege reaches level 5. Nothing further in the tree depends on it, so it is a leaf: worth taking for its own bonus, never as a stepping stone.
The road here: Weaponry to level 3 → Armor to level 8 → Fortification to level 5 → Stonework to level 8 → Moat Works to level 5 → Deep Cisterns. That is 5 studies standing between a fresh Academy and this one.
| Prerequisite | Level required | Each resource | Study time |
|---|---|---|---|
| Weaponry | 3 | 47,880 | 40m 47s |
| Armor | 8 | 286,292 | 4h 3m |
| Fortification | 5 | 108,517 | 1h 32m |
| Stonework | 8 | 286,292 | 45m 44s |
| Moat Works | 5 | 108,517 | 20m 13s |
| Total before you may begin | — | 837,498 | 7h 23m |
Numerically twinned with Concentric Castles. Same cap, same rate per level, same study time, same power — the figures on those pages match these exactly. What separates them is the flavour and, more usefully, what each one gates: this one opens nothing further, while Concentric Castles opens The Long Memory. If you only want the bonus, take whichever is cheaper to reach; if you are building toward something, take the one that gates it.
Related
Guide: Research & the Academy · Research Priorities. Studied at the Maester's Academy. Index: all 81 studies · the whole database.
Rest of the Defense branch: Fortification · Siege Craft · Palisades · Stonework · Watchtowers · Moat Works · Battlements · Portcullis · Curtain Walls · Barbicans · Gatehouses · Counter-Siege · Murder Holes · Arrow Slits · Siege Engineering · Concentric Castles · Bombardment Doctrine
Every figure above is generated from the shipped game code — the same constants and formulas the running game uses — and regenerated whenever the balance changes. Nothing on this page is hand-typed.