Idle Defense Guide: The basic loop
About
OverviewIdle Defense is a tower defense idle game on Roblox where you place units on your plot and they fight off waves of zombies automatically. Your job is to manage placement, spend the cash your units earn on stronger units, and push into harder areas. This guide covers how to get started, how to strengthen your units through Evolution, and how to collect free items from codes.
What is on this page
Contents
The basic loop
Step
Follow these steps each session to keep moving forward.
- Place units on your plot they attack zombies automatically from the moment you set them down.
- Earn cash every zombie your units kill drops money directly into your wallet.
- Unlock stronger units spend that cash in the unit shop to access more powerful options.
- Push into new areas once your lineup can handle the current wave, unlock the next area and face tougher enemies.
- Check the Merchant the shop on your plot restocks every three hours with five item slots, so log in regularly to grab Evolution materials.
MetaNew Player Survey
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Unit rarities at a glance
SummaryUnits in Idle Defense are sorted into tiers from Common up to Secret, plus special categories like Seasonal, Ascendant, and Admin.
- Common examples include Noob Knight and Rusty Turret.
- Rare examples include Ranger, Freezer, and Fallen Knight.
- Epic examples include Archer, Cowboy, and Grenadier.
- Legendary examples include Railgunner, Rocketeer, and Builderman.
- Mythic examples include Ember, Demon, and Frost Queen.
- Secret examples include Executioner and Astral Angel.
- Ascendant examples include Frog Mech and Triple T.
Flying and hidden enemies
Warn
Not every unit can hit every enemy. The Digital wave introduces flying zombies that can only be damaged by units capable of detecting flying targets. Hidden zombies work the same way — only units that detect hidden enemies can hit them.
Evolution — turning units into stronger forms
TipsTo evolve a unit, bring the base unit and its required item to the Evolution Machine. Each recipe is fixed — the wrong item does nothing.
- Freezer plus a Golden Aura becomes Golden Freezer.
- Business Man plus a Golden Aura becomes Golden Business Man.
- Railgunner plus a Golden Aura becomes Golden Railgunner.
- Signal plus a Golden Aura becomes Golden Signal.
- Outlaw plus a Golden Aura becomes Golden Outlaw.
- Demon plus a Golden Aura becomes Angel, and Angel plus an Astral Star becomes Astral Angel.
- Fallen Knight plus an Astral Star becomes Astral Knight.
- Ember plus a Dark Aura becomes Dark Ember at the Evolution Shrine.
- Dark Aura can also evolve Guest into The Guest, Knight into Fallen Knight, and Farmer into Infected Farmer.
- Infected Farmer plus a Tree Root upgrades to a stronger Infected Farmer form — get Tree Roots from Infected boss waves.
- King plus a Crown becomes Overlord; the Crown was sold in the Merchant during the Medieval event for $25M.
Where to find Evolution materials
TableKnowing where to look saves you from waiting on the wrong activity.
| Golden Aura | buy directly from Merchant slots using Bucks; restocks every three hours. |
| Astral Star | appears rarely as a high-priced Merchant slot; costs $25M per star. |
| Dark Aura | drops from z.o.m.b.i.e enemies and given by certain codes. |
| Tree Root | drops from Infected boss wave enemies. |
| King's Crown | rewarded by defeating the King boss, which you summon using Boss Lures. |
| Mask | five percent drop chance from Masquerade enemies that rarely appear during Act 2 Wave 1; used to evolve Drama. |
| Executioner Axe | the secret Executioner boss itself has a 0.01% spawn chance, and the axe drops at another 0.01% from that boss. |
Redeem codes
StepNew codes are announced in the game's official Discord server. Codes can also be found via the community server on Discord.
- Open the code box find the input field in the bottom-left corner of your screen.
- Type the code exactly as shown.
- Do not retry expired codes a code that has expired will not give you anything.
BROCKTHEPIRATE
FREE50DARKAURA2
SUMMEREVENT25
FREE50DARKAURA1
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[⚡EVENT] Idle Defense
Glossary
Glossary- Plot
- Your personal area where you place units to defend against incoming zombie waves.
- Evolution Machine
- The machine where you combine a base unit with its required item to produce a stronger evolved unit.
- Evolution Shrine
- A separate machine used for Dark Aura evolutions such as turning Ember into Dark Ember.
- Merchant
- A shop that spawns on your plot and refreshes five random item slots every three hours.
- Golden Aura
- An evolution material bought from the Merchant using Bucks, used to upgrade several standard units.
- Astral Star
- A rare, high-priced Merchant item costing $25M, used to evolve Astral Demon into Astral Angel and Fallen Knight into Astral Knight.
- Dark Aura
- An item dropped by z.o.m.b.i.e enemies and given by codes, used for enchanting and certain evolutions.
- Boss Lure
- An item that lets you summon specific bosses like King so you can fight them for their drops.
- Bucks
- The in-game currency used to buy items from the Merchant.
- Ascendant
- A special rarity containing Frog Mech and Triple T.
Common questions
FAQWhere do I enter a redeem code?
Look at the bottom-left corner of your screen in-game and you will find the code input field there.
How do I get the Executioner Axe?
The secret Executioner boss has a 0.01% chance to spawn, and the axe itself drops at a 0.01% chance when you kill that boss.
Why can my strong unit not damage some enemies?
Units have detection types — some only detect hidden enemies, others only detect flying ones. If a zombie type does not match your unit's detection, the unit will not target it at all.
Where can I find the newest codes?
Codes are announced in the game's official Discord server.
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