Each tree is bought from the bottom up: an upgrade can be bought once the one below it is. Every upgrade applies to the battles played from then on; the Heroic and Iron Challenges of stages 1 to 10 use each tree only up to a set level. The Reset button in the Upgrades room gives back every star spent.
Tier 1
Archers
Archers tree
5 upgrades, 9 stars in all.
Barracks
Barracks tree
5 upgrades, 9 stars in all.
Mages
Mages tree
5 upgrades, 9 stars in all.
Artillery
Artillery tree
5 upgrades, 10 stars in all.
Rain of Fire
Rain of Fire tree
5 upgrades, 13 stars in all.
Reinforcements
Reinforcements tree
5 upgrades, 15 stars in all.
Tier 2
Salvage
Archers level 1
Selling an archer tower returns 90% of the gold spent on it instead of 60%. Applies to Archer Tower, Marksman Tower, Sharpshooter Tower, Rangers Hideout and Musketeer Garrison.
1 star
Requires: Archers
Toughness Training
Barracks level 1
Barracks soldiers get 10% more health: Militia Barracks 50 to 55, Footmen Barracks 100 to 110, Knights Barracks 150 to 165, Holy Order 200 to 220, Barbarian Hall 250 to 275.
Requires: Barracks
Spell Reach
Mages level 1
+10% attack range for every mage tower (Mage Tower 140 to 154, Arcane Wizard 200 to 220).
Requires: Mages
Concentrated Fire
Artillery level 1
+10% damage for artillery towers: Dwarven Bombard 8-15 to 9-17, Dwarven Artillery 20-40 to 22-44, Dwarven Howitzer 30-60 to 33-66, 500mm Big Bertha 50-100 to 55-110, Tesla x104 26 or 39 to 26, 39 or 52 per enemy hit.
Requires: Artillery
Blazing Skies
Rain of Fire level 1
5 meteors instead of 3, and meteor damage 30-60 to 50-80.
Requires: Rain of Fire
Well Fed
Reinforcements level 1
The farmers are well fed: health 30 to 50 on Normal, damage 1-2 to 1-3, healing 3 to 6 health per second.
Requires: Reinforcements
Tier 3
Eagle Eye
Archers level 2
+10% attack range for every archer tower (Archer Tower 140 to 154, Rangers Hideout 200 to 220); the Rangers Hideout's Wrath of the Forest area grows by 10% too.
Requires: Salvage
Better Armor
Barracks level 2
+10 armor for barracks soldiers: Militia Barracks 0% to 10%, Footmen Barracks 15% to 25%, Knights Barracks 30% to 40%, Holy Order 50% to 60%, Barbarian Hall 0% to 10%.
Requires: Toughness Training
Arcane Shatter
Mages level 2
Every hit of a mage tower lowers the target's armor by 3 points for the rest of the battle (60% becomes 57%), down to 0. Elora Wintersong's and Magnus Spellbane's bolts do it too.
Requires: Spell Reach
Range Finder
Artillery level 2
+10% attack range for every artillery tower, rounded up (Dwarven Bombard 160 to 176, 500mm Big Bertha 180 to 199).
Requires: Concentrated Fire
Scorched Earth
Rain of Fire level 2
Each meteor leaves burning ground for 5 s: 10-20 physical damage every 1 s to ground enemies on it. Flying enemies do not burn.
Requires: Blazing Skies
Conscripts
Reinforcements level 2
The two soldiers are conscripts: health 50 to 70 on Normal, armor 0% to 10%, damage 1-3 to 2-4, healing 6 to 9 health per second.
Requires: Well Fed
Tier 4
Piercing Shots
Archers level 3
Archer tower shots ignore 10 points of the target's armor: an enemy with 60% armor takes them as if it had 50%. Applies to the arrows of Archer Tower, Marksman Tower, Sharpshooter Tower and Rangers Hideout and to both Musketeer Garrison shots.
Requires: Eagle Eye
Improved Deployment
Barracks level 3
A fallen soldier is replaced 20% sooner (10 s to 8 s; Holy Order paladins 14 s to 11 s), and the rally point range grows 20% (145 to 174) for every barracks, the Sylvan Elf included.
Requires: Better Armor
Hermetic Study
Mages level 3
Mage towers cost 10% less to build and upgrade: Mage Tower 100 to 90 gold, Adept Tower 160 to 144 gold, Wizard Tower 240 to 216 gold, Arcane Wizard 300 to 270 gold, Sorcerer Mage 300 to 270 gold.
Requires: Arcane Shatter
Field Logistic
Artillery level 3
Artillery towers cost 10% less to build and upgrade (rounded down): Dwarven Bombard 125 to 112 gold, Dwarven Artillery 220 to 198 gold, Dwarven Howitzer 320 to 288 gold, 500mm Big Bertha 400 to 360 gold, Tesla x104 375 to 337 gold.
Requires: Range Finder
The Fast & Furious
Rain of Fire level 3
Meteor damage 50-80 to 90-120, blast radius 60 to 75 (+25%), cooldown 80 s to 70 s.
Requires: Scorched Earth
Warriors
Reinforcements level 3
The two soldiers are warriors: health 70 to 90 on Normal, armor 10% to 20%, damage 2-4 to 3-6, healing 9 to 12 health per second.
Requires: Conscripts
Tier 5
Far Shots
Archers level 4
Another +10% attack range for every archer tower (Archer Tower 154 to 169.4, Rangers Hideout 220 to 242); the Rangers Hideout's Wrath of the Forest area grows by 10% too. With Eagle Eye the range is 21% above the base.
Requires: Piercing Shots
Endurance Training
Barracks level 4
Barracks soldiers get more health again, 20% above the base in all: Militia Barracks 55 to 60, Footmen Barracks 110 to 120, Knights Barracks 165 to 180, Holy Order 220 to 240, Barbarian Hall 275 to 300.
Requires: Improved Deployment
Empowered Magic
Mages level 4
+15% damage for mage towers (rounded up): Mage Tower 10-17 to 12-20, Adept Tower 24-43 to 28-50, Wizard Tower 41-74 to 47-86, Arcane Wizard 76-140 to 88-161, Sorcerer Mage 43-78 to 50-90.
Requires: Hermetic Study
Industrialization
Artillery level 4
The abilities of the 500mm Big Bertha and the Tesla x104 cost 25% less (rounded down): a 250 gold ability level costs 187.
Requires: Field Logistic
Blazing Earth
Rain of Fire level 4
The burning ground lasts 10 s instead of 5 s and deals 20-30 damage every 1 s instead of 10-20; cooldown 70 s to 60 s.
Requires: The Fast & Furious
Legionnaires
Reinforcements level 4
The two soldiers are legionnaires: health 90 to 110 on Normal, armor 20% to 30%, damage 3-6 to 6-10, healing 12 to 15 health per second.
Requires: Warriors
Tier 6
Precision
Archers level 5
Each shot has a 10% chance to deal 2x damage. Applies to the arrows of every Archer Tower level and the Rangers Hideout and to the Musketeer Garrison's normal shots, not its Sniper Shot; Bolin Farslayer's shotgun gets it too.
Requires: Far Shots
Spiked Armor
Barracks level 5
When a soldier is hit, the enemy it is fighting takes 10% of that hit back as true damage (rounded up). Covers barracks soldiers, Sylvan Elves, the Sasquatch, The Citadel's Imperial Guards, reinforcements, every hero and the units heroes and towers summon.
Requires: Endurance Training
Slow Curse
Mages level 5
Every hit of a mage tower slows the target to 50% speed for 0.5 s. It does not work on an enemy that is already slowed or enraged. Magnus Spellbane's bolts do it too. Cerberus is never slowed.
Requires: Empowered Magic
Smart Targeting
Artillery level 5
Bomb blasts deal their full damage to every enemy caught in them; without it, damage falls from the maximum at the centre to the minimum at the edge. The Tesla x104's lightning deals its full damage on every enemy it hits instead of half (52, 65, 78, 91 or 104 per enemy hit with Concentrated Fire). The blasts of the Musketeer Garrison's Shrapnel Shot and of the Dynamite item count as bombs too.
Requires: Industrialization
Cataclysm
Rain of Fire level 5
Meteor damage 90-120 to 150-180, and 5 more meteors fall at random places on the battlefield.
Requires: Blazing Earth
Spear Throw
Reinforcements level 5
The legionnaires throw spears at ground and flying enemies: 25-40 physical damage every 1.4 s, from 27 to 165 away. Their other stats stay the same.
Requires: Legionnaires
The six trees
The Archers tree: 5 upgrades, 9 stars in all.
| Upgrade | Stars | Effect |
|---|---|---|
| 1. Salvage | 1 | Selling an archer tower returns 90% of the gold spent on it instead of 60%. Applies to Archer Tower, Marksman Tower, Sharpshooter Tower, Rangers Hideout and Musketeer Garrison. |
| 2. Eagle Eye | 1 | +10% attack range for every archer tower (Archer Tower 140 to 154, Rangers Hideout 200 to 220); the Rangers Hideout's Wrath of the Forest area grows by 10% too. |
| 3. Piercing Shots | 2 | Archer tower shots ignore 10 points of the target's armor: an enemy with 60% armor takes them as if it had 50%. Applies to the arrows of Archer Tower, Marksman Tower, Sharpshooter Tower and Rangers Hideout and to both Musketeer Garrison shots. |
| 4. Far Shots | 2 | Another +10% attack range for every archer tower (Archer Tower 154 to 169.4, Rangers Hideout 220 to 242); the Rangers Hideout's Wrath of the Forest area grows by 10% too. With Eagle Eye the range is 21% above the base. |
| 5. Precision | 3 | Each shot has a 10% chance to deal 2x damage. Applies to the arrows of every Archer Tower level and the Rangers Hideout and to the Musketeer Garrison's normal shots, not its Sniper Shot; Bolin Farslayer's shotgun gets it too. |
The Barracks tree: 5 upgrades, 9 stars in all.
| Upgrade | Stars | Effect |
|---|---|---|
| 1. Toughness Training | 1 | Barracks soldiers get 10% more health: Militia Barracks 50 to 55, Footmen Barracks 100 to 110, Knights Barracks 150 to 165, Holy Order 200 to 220, Barbarian Hall 250 to 275. |
| 2. Better Armor | 1 | +10 armor for barracks soldiers: Militia Barracks 0% to 10%, Footmen Barracks 15% to 25%, Knights Barracks 30% to 40%, Holy Order 50% to 60%, Barbarian Hall 0% to 10%. |
| 3. Improved Deployment | 2 | A fallen soldier is replaced 20% sooner (10 s to 8 s; Holy Order paladins 14 s to 11 s), and the rally point range grows 20% (145 to 174) for every barracks, the Sylvan Elf included. |
| 4. Endurance Training | 2 | Barracks soldiers get more health again, 20% above the base in all: Militia Barracks 55 to 60, Footmen Barracks 110 to 120, Knights Barracks 165 to 180, Holy Order 220 to 240, Barbarian Hall 275 to 300. |
| 5. Spiked Armor | 3 | When a soldier is hit, the enemy it is fighting takes 10% of that hit back as true damage (rounded up). Covers barracks soldiers, Sylvan Elves, the Sasquatch, The Citadel's Imperial Guards, reinforcements, every hero and the units heroes and towers summon. |
The Mages tree: 5 upgrades, 9 stars in all.
| Upgrade | Stars | Effect |
|---|---|---|
| 1. Spell Reach | 1 | +10% attack range for every mage tower (Mage Tower 140 to 154, Arcane Wizard 200 to 220). |
| 2. Arcane Shatter | 1 | Every hit of a mage tower lowers the target's armor by 3 points for the rest of the battle (60% becomes 57%), down to 0. Elora Wintersong's and Magnus Spellbane's bolts do it too. |
| 3. Hermetic Study | 2 | Mage towers cost 10% less to build and upgrade: Mage Tower 100 to 90 gold, Adept Tower 160 to 144 gold, Wizard Tower 240 to 216 gold, Arcane Wizard 300 to 270 gold, Sorcerer Mage 300 to 270 gold. |
| 4. Empowered Magic | 2 | +15% damage for mage towers (rounded up): Mage Tower 10-17 to 12-20, Adept Tower 24-43 to 28-50, Wizard Tower 41-74 to 47-86, Arcane Wizard 76-140 to 88-161, Sorcerer Mage 43-78 to 50-90. |
| 5. Slow Curse | 3 | Every hit of a mage tower slows the target to 50% speed for 0.5 s. It does not work on an enemy that is already slowed or enraged. Magnus Spellbane's bolts do it too. Cerberus is never slowed. |
The Artillery tree: 5 upgrades, 10 stars in all.
| Upgrade | Stars | Effect |
|---|---|---|
| 1. Concentrated Fire | 1 | +10% damage for artillery towers: Dwarven Bombard 8-15 to 9-17, Dwarven Artillery 20-40 to 22-44, Dwarven Howitzer 30-60 to 33-66, 500mm Big Bertha 50-100 to 55-110, Tesla x104 26 or 39 to 26, 39 or 52 per enemy hit. |
| 2. Range Finder | 1 | +10% attack range for every artillery tower, rounded up (Dwarven Bombard 160 to 176, 500mm Big Bertha 180 to 199). |
| 3. Field Logistic | 2 | Artillery towers cost 10% less to build and upgrade (rounded down): Dwarven Bombard 125 to 112 gold, Dwarven Artillery 220 to 198 gold, Dwarven Howitzer 320 to 288 gold, 500mm Big Bertha 400 to 360 gold, Tesla x104 375 to 337 gold. |
| 4. Industrialization | 3 | The abilities of the 500mm Big Bertha and the Tesla x104 cost 25% less (rounded down): a 250 gold ability level costs 187. |
| 5. Smart Targeting | 3 | Bomb blasts deal their full damage to every enemy caught in them; without it, damage falls from the maximum at the centre to the minimum at the edge. The Tesla x104's lightning deals its full damage on every enemy it hits instead of half (52, 65, 78, 91 or 104 per enemy hit with Concentrated Fire). The blasts of the Musketeer Garrison's Shrapnel Shot and of the Dynamite item count as bombs too. |
The Rain of Fire tree: 5 upgrades, 13 stars in all.
| Upgrade | Stars | Effect |
|---|---|---|
| 1. Blazing Skies | 2 | 5 meteors instead of 3, and meteor damage 30-60 to 50-80. |
| 2. Scorched Earth | 2 | Each meteor leaves burning ground for 5 s: 10-20 physical damage every 1 s to ground enemies on it. Flying enemies do not burn. |
| 3. The Fast & Furious | 3 | Meteor damage 50-80 to 90-120, blast radius 60 to 75 (+25%), cooldown 80 s to 70 s. |
| 4. Blazing Earth | 3 | The burning ground lasts 10 s instead of 5 s and deals 20-30 damage every 1 s instead of 10-20; cooldown 70 s to 60 s. |
| 5. Cataclysm | 3 | Meteor damage 90-120 to 150-180, and 5 more meteors fall at random places on the battlefield. |
The Reinforcements tree: 5 upgrades, 15 stars in all.
| Upgrade | Stars | Effect |
|---|---|---|
| 1. Well Fed | 2 | The farmers are well fed: health 30 to 50 on Normal, damage 1-2 to 1-3, healing 3 to 6 health per second. |
| 2. Conscripts | 3 | The two soldiers are conscripts: health 50 to 70 on Normal, armor 0% to 10%, damage 1-3 to 2-4, healing 6 to 9 health per second. |
| 3. Warriors | 3 | The two soldiers are warriors: health 70 to 90 on Normal, armor 10% to 20%, damage 2-4 to 3-6, healing 9 to 12 health per second. |
| 4. Legionnaires | 3 | The two soldiers are legionnaires: health 90 to 110 on Normal, armor 20% to 30%, damage 3-6 to 6-10, healing 12 to 15 health per second. |
| 5. Spear Throw | 4 | The legionnaires throw spears at ground and flying enemies: 25-40 physical damage every 1.4 s, from 27 to 165 away. Their other stats stay the same. |
Stars per tree
| Tree | Upgrades | Stars |
|---|---|---|
| Archers | 5 | 9 |
| Barracks | 5 | 9 |
| Mages | 5 | 9 |
| Artillery | 5 | 10 |
| Rain of Fire | 5 | 13 |
| Reinforcements | 5 | 15 |
| All trees | 30 | 65 |
Upgrades in Heroic and Iron challenges
The Heroic and Iron challenges of stages 1 to 10 use the Upgrades room only up to a set level in each tree; upgrades above it do nothing in that battle.
| Challenge | Highest upgrade level |
|---|---|
| Stage 1 | Level 1 |
| Stages 2-4 | Level 2 |
| Stages 5-7 | Level 3 |
| Stages 8-10 | Level 4 |
| Stage 11 and later | All 5 levels |