King of Stone Build Guide: Ballista Fortress
A King of Stone build for 9 Kings 1.0: Stronghold, Ballista, Quarry, and the tower stacking that makes Stone the safest defensive king in the game.
Quick answer: The King of Stone build stacks towers. Stronghold summons them, Ballista pierces, Quarry buffs every tower and base, and Bunker makes them fire faster. It is the best defensive build in 9 Kings and the easiest to pilot.
Stone is the fortress king. Its cards are towers, walls, and buildings that make towers better. It does not have a flashy carry or a complex combo. It has a board that shoots everything that walks toward it.
That makes it the most forgiving build in the game and a strong choice for players who prefer defense.
The deck
Stone's nine cards:
- Stronghold (base): summons towers.
- Ballista (troop): fires a piercing bolt.
- Trebuchet (building): each building adds +1 rock.
- Cauldron (building): adjacent attacks apply poison.
- Quarry (building): +2% damage per year to all towers and bases.
- Earthworks (building): unlocks an adjacent plot; returns up to three cards.
- Wallmaker (building): creates a wall.
- Flametower (tower): a mobile flamethrower.
- Trapper (building): traps stack across battles.
The deck has one summoner, four towers, and enough support to make every tower count.
The Ballista Fortress engine
The core loop:
- Stronghold summons towers.
- Quarry buffs every tower and base.
- Trebuchet adds a rock for each building.
- Bunker (decree) makes towers fire faster.
The result is a board that does not need a melee carry. Towers cannot be attacked or destroyed, so they keep shooting even when the front line collapses. That is the defining strength of Stone.
Opening priorities
Years 1–3: take Stronghold if it appears. If not, take Ballista or Quarry. You need a tower source before you need a payoff.
Year 4: take Bunker if it appears. It is the best Stone decree by a wide margin.
Years 5–7: place Quarry next to your towers. Place a wall in front of the base.
Years 8–11: save gold. Stone wants a second tower at year 12.
Year 12: buy Ballista, Flametower, or a second Quarry.
The full board
By year 20:
- Base plot: Stronghold.
- Carry plot: Ballista or Flametower, behind a wall.
- Support plots: Quarry and Trebuchet.
- Front line: Wallmaker walls and a cheap body.
- Kill zone: overlapping tower range.
- Open plot: a second Quarry or a Trapper.
The wall is not optional. Towers cannot block, so you need something to stop the enemy from reaching the base.
Decrees
The best decrees for Stone:
- Bunker: +50% tower attack speed. The best Stone decree.
- Sharp Blades: +30% attack. Towers benefit.
- Exploration: extra plots. Stone needs room for towers.
- Gunpowder: +30% area radius. Good with Flametower and Trebuchet.
Avoid Feast. Stone's units are not the damage.
Perks
The Stone perks that matter:
- Incendiary: +10% Flametower area.
- Hurler: +1 Trebuchet rock.
- Tactician: +1 random tower card.
- Impervious: +10% tower HP. Towers cannot be attacked, but the buff helps Stronghold.
- Ballisteer: +10% Ballista damage.
Universal: Ingenious, Expansionist, Persistent, Fortifier, and Castellan. Fortifier is the best universal for this build.
Matchups and card swaps
Stone's plan changes less than most builds, but the order of your support does change.
Against Blood, keep Flametower behind the wall and spread Quarry so Carnage explosions cannot delete your damage. The imps die to overlapping tower fire; do not chase them with Ballista.
Against Progress, kill the Lab Rat's support plots before the rat itself. Ballista's pierce is good here because Progress often stacks support in a line. If the rat is already huge, add a second wall and accept a longer fight.
Against Spells, spread your towers by one plot. Static chains jump between adjacent units, and a tight tower cluster gives the Wizard free value. A Trapper on the flank is better than a third Quarry in this matchup.
Against Time, save Bunker for the second half of the fight. Portal can undo your first push, and Hourglass rewards the long battle. Do not spend all your gold on a year you may replay.
Against Nature, keep your walls repaired and target the Boar with Ballista. Nature's damage comes from one unit; if the Boar dies, the board collapses. Do not spread fire across the Treants.
If you never see Stronghold by year 12, buy Flametower and play a slower two-tower board. Do not force Ballista without a wall.
The Final Battle
Stone is one of the safest Final Battle builds because towers cannot be destroyed. The boss can kill your walls and your body, but it cannot kill the towers that are shooting it.
The weakness is time. If the boss reaches your base before the towers kill it, you lose. Stack Bunker, Quarry, and Sharp Blades, and keep a wall in front.
Common mistakes
No wall. Towers cannot block. Without a wall, the boss walks past them.
Building towers in front. Towers have range; putting them forward wastes it.
Ignoring Quarry. Quarry is the multiplier. A board of unbuffed towers is much weaker.
Taking Feast. Stone does not need HP. It needs attack speed and damage.
The best decrees→ page explains why Bunker is build-defining, and the kingdom layout→ page shows the fortress shape.
A wall with no towers is survivable. Towers with no wall are not.
FAQ
Is King of Stone good in 9 Kings? Yes. It is the best defensive king and the easiest build to pilot.
What is the best Stone build? Ballista Fortress: Stronghold, Ballista, Quarry, Trebuchet, Wallmaker.
Do towers need protection? No. Towers cannot be attacked or destroyed. Your base and walls need protection.
How do I unlock King of Stone? Build 99 buildings across your runs.
Sources
Official source: 9 Kings Steam store page ↗