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Shop
The shop will offer 4 random items. These items will depend on your character, 
Luck, number of waves progressed and if you have chosen to lock it. Each item has a cost depending on its rarity and their base value. You can purchase unique items once.
Mechanics
Reroll
You can Reroll the four given options you're given both when leveling up and in the Shop. This gives you four new fresh options, Unless you've Locked an item in the shop. Rerolling costs an amount of Materials that depends on the Current wave. Each additional reroll has its cost increased by a flat amount that also depends on the current wave. See the table below.
The price for rerolls, resets between shops and level ups. So rerolling in one shop doesn't affect the prices of rerolling in the next shop. And rerolling your level ups doesn't affect the cost of rerolling in the shop. However, if you gain 2 or more levels in one wave, the reroll price is shared between the level ups.
The item 
Dangerous Bunny gives you +1 Free reroll in the shop for each bunny you have. So if you have 3 Dangerous Bunnies, you can reroll the shop 3 times for 0 Materials each shop. The free rerolls doesn't increase the price of subsequent rerolls, so the price of the 4th reroll is unchanged. It costs the same as if it was your first reroll.
Buying all 4 items in the Shop reduces the cost of the current reroll to 0. However unlike the free rerolls from Dangerous Bunny, the price of the next reroll is still increased.
However, for the round when you buy a Dangerous Bunny in a shop, it reduces the cost of the current reroll, instead of granting a "free rerolL".
Reroll Price
The Reroll Increase is calculated as follows:
Reroll Increase: Rounddown(max(0.5 * wave))
and the price of the first reroll is:
First Reroll Price: Wave + Reroll Increase
Notes:
- The max function is used to ensure that the price of rerolling is at least 1, and at least increases by 1 with each wave.
- In Endless Mode the reroll price is multiplied by the endless Factor. See Endless Mode Rerolling for costs at higher levels.
- Every reroll increases the price by the reroll price.
So at the end of wave 5, with the upgrades and shop that follows, the reroll increase is 0.5 * 5 = 2.5, which is rounded down to 2. So the first reroll costs 5+2, and each following reroll increases by +2.
Here are a table over reroll costs for the 20 waves.
| Wave | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| First Reroll Price | 2 | 3 | 4 | 6 | 7 | 9 | 10 | 12 | 13 | 15 | 16 | 18 | 19 | 21 | 22 | 24 | 25 | 27 | 28 | N/A |
| Price Increase per Reroll | 1 | 1 | 1 | 2 | 2 | 3 | 3 | 4 | 4 | 5 | 5 | 6 | 6 | 7 | 7 | 8 | 8 | 9 | 9 | N/A |
Locking
You can lock and unlock items by clicking the lock under each item. Locking is free and can be done as often as you like. While an item is locked, it will stay in the shop when the shop is rerolled and it will also stay in the shop between waves if you begin the next wave. If you keep an item locked between waves, its price also remains locked and isn't increased by inflation.
While an item is locked, that item cannot appear in the other slots in the shop, and it cannot be found in Loot Crates. (Fisherman locking Bait is the one exception, where you will still get your guaranteed Bait on a reroll.)
Combining
If you have two identical weapons equipped, you can click one of the weapons and choose combine. This combines the weapon with another weapon of same type and tier into one weapon of one higher tier.
Also, if you have filled your weapon slots and buy a weapon that is identical to one you have in your weapon slots, the two will automatically combine to the same weapon of one higher tier.
For example, two Tier 1 
Knife can be combined into one Tier 2 Knife
And finally weapons cannot be combined above Tier 4
Recycling
You can recycle your Weapons and Items found in Crates to get a percentage of their value back, at the cost of losing the item or weapon.
The default is to get 25% back when recycling. 
Recycling Machine can increase this value by 35% for a total of 60% back.
This stacks with the +25% from 
Entrepreneur for a total of 85%. Rewards for recycling are based upon the current price of the item, so it increases with inflation, but decreases if you have coupons, since it scales with your shop price secondary stat.
In Endless Mode, Shop Prices increases sharply by the Endless Factor, but the increase isn't applied to the recycling value.
Elite and Swarm Radar
On danger 2+ the shop will display which waves contain which waves have swarms or elites in. See Elite and Horde Waves
Shop Prices And Inflation
Each item or weapon has a base price. When you see the item/weapon in the shop it will have inflation applied to its price. Even the first shop has already have inflation applied.
The equation is:
Final Price = (Base_Price + Wave + (Base_Price * 0.1 * Wave)) * Shop_Price
Note that:
- Items have a minimum cost of 1 Materials. The Price is also Rounded Down.
- Wave is the current wave. When you finish wave 5, it means that 5 is used as the number for the following shop.
- Shop_Price is the secondary stat affected by
Coupon and characters with changed shop prices like 
Mutant - Base_Price is the base price of items. You can see the base price of items at the Items and the Weapons Pages. This base price can be modified by
Arms Dealer. - In Endless Mode the Item Price also increases with the Endless Factor.
This Final Price is the price you will see in shops, and it is also the value that is used for recycling. The increase in price with each wave is referred to as the Inflation of prices.
So for example, a 
SMG has a base price of 20. So when we see it in the first shop, its price is:
SMG Price = 20 + 1 + (20 * 0.1 * 1) * 100% = 20 + 1 + 2 = 23.
And in another example, We see a 
Cyclops Worm (45 base price) in the 5th shop.
Cyclops Worm Price = 45 + 5 + (45 * 0.1 * 5) * 100% = 50 + 22.5 = 72.5
The Final price is then rounded down, and it will cost 72. If you had 2 Coupon's
72.5 * 90% = 65.25 = Final Price 65
Since the Equation includes + Wave addition to the 10%, cheaper items will be hit harder by inflation, and will be slightly less cost effective late game.
Locked items are not affected by inflation if you keep them locked between shops.
Rarity of Shop Items and Luck
Here is a table over the progression of the rarity of items and weapons in the shop. The Shops appear at the end of each wave. So at the end of wave 1, the first shop appears. You can see the Shop number in the top left corner of the shop.
Available From Wave tells you the first wave where you can encounter the rarity.
| Available From Wave | Min Wave | Base Chance | +Chance per Wave | Max Chance | |
|---|---|---|---|---|---|
| Tier 1 | 1 | 1 | 100% | 0% | 100% |
| Tier 2 | 2 | 1 | 0% | 6% | 60% |
| Tier 3 | 4 | 3 | 0% | 2% | 25% |
| Tier 4 | 8 | 7 | 0% | 0.23% | 8% |
Calculation for chances are done by:
= ((Chance per Wave * (Current Wave - Min Wave)) + Base Chance) * (100%+Luck)
Chance per wave starts adding chance after the Min Wave.
This value cannot exceed Max Chance.
Rarities with 0 Luck
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tier 1 | 100% | 94% | 88% | 80% | 72% | 64% | 56% | 47.77% | 39.54% | 31.31% | 23.08% | 20.85% | 18.62% | 16.39% | 14.16% | 12.93% | 12.7% | 12.47% | 12.24% |
| Tier 2 | 0% | 6% | 12% | 18% | 24% | 30% | 36% | 42% | 48% | 54% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% |
| Tier 3 | 0% | 0% | 0% | 2% | 4% | 6% | 8% | 10% | 12% | 14% | 16% | 18% | 20% | 22% | 24% | 25% | 25% | 25% | 25% |
| Tier 4 | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0.23% | 0.46% | 0.69% | 0.92% | 1.15% | 1.38% | 1.61% | 1.84% | 2.07% | 2.3% | 2.53% | 2.76% |
Luck increases these chances by x%, but that still cannot exceed the Max Chance.
For example:
- In wave 10 with 0 Luck, the chance for Tier 3 is 2*7 = 14% -- extrapolated: ( 2% * ( 10 - 3 ) + 0% ) * ( 100% + 0% )
- In wave 10 with 50 Luck, it increases by 50%, 2*10.5 = 21% -- extrapolated: ( 2% * ( 10 - 3 ) + 0% ) * ( 100% + 50% )
- In wave 10 with 100 Luck, it increases by 100%, 2*14 = 28% -- extrapolated: ( 2% * ( 10 - 3 ) + 0% ) * ( 100% + 100% )
- However, Max Chance for Tier 3 is 25%, so the chance for Tier 3 ends up as 25%.
Rarities with 50 Luck
Increases chances by 50% (*1.5), up to the Max Chance.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tier 1 | 100% | 91% | 82% | 70% | 58% | 46% | 34% | 24.66% | 21.31% | 17.96% | 14.62% | 13.28% | 12.93% | 12.59% | 12.24% | 11.89% | 11.55% | 11.21% | 10.86% |
| Tier 2 | 0% | 9% | 18% | 27% | 36% | 45% | 54% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% |
| Tier 3 | 0% | 0% | 0% | 3% | 6% | 9% | 12% | 15% | 18% | 21% | 24% | 25% | 25% | 25% | 25% | 25% | 25% | 25% | 25% |
| Tier 4 | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0.35% | 0.69% | 1.04% | 1.38% | 1.73% | 2.07% | 2.42% | 2.76% | 3.11% | 3.45% | 3.8% | 4.14% |
Rarities with 100 Luck
Increases chances by 100% (*2), up to the Max Chance.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tier 1 | 100% | 88% | 76% | 60% | 44% | 28% | 24% | 19.54% | 15.08% | 13.62% | 13.16% | 12.7% | 12.24% | 11.78% | 11.32% | 10.86% | 10.4% | 9.94% | 9.48% |
| Tier 2 | 0% | 12% | 24% | 36% | 48% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% | 60% |
| Tier 3 | 0% | 0% | 0% | 4% | 8% | 12% | 16% | 20% | 24% | 25% | 25% | 25% | 25% | 25% | 25% | 25% | 25% | 25% | 25% |
| Tier 4 | 0% | 0% | 0% | 0% | 0% | 0% | 0% | 0.46% | 0.92% | 1.38% | 1.84% | 2.3% | 2.76% | 3.22% | 3.68% | 4.14% | 4.6% | 5.06% | 5.52% |
Item & Weapon Chances
Item/Weapon Chance
Most waves have a fixed chance for either an Item or Weapon to appear in the Shop:
However, early rounds guarantee a weapon to appear:
- First two Shops (Wave 1,2): Guaranteed 2 Weapons + 2 Items.
- The Next three Shops (Wave 3,4,5): Guaranteed 1 Weapon + 3 other purchasables (ie. either a weapons or items).
- Rest of the Shops (Wave 6+): No guarantees.
Item Tags
Characters with "wanted tags" (which are Item Tags that suit their playstyle) have a higher chance to find an item with that tag:
Whenever an item appears in the shop, it has a 5% chance to be selected from an item pool of your tagged items, instead of the regular item pool. This guarantees that the item has one of your character's tags.
- Considering the 65% for a item, the actual chance is: 3.25% per slot in the shop to give you an item through the Tag System.
Note that tagged items are found both in their tagged item pool, but also in the general item pool. So if the 5% chance doesn't happen, you can still find those same items in the general item pool with all the items in the game.
Weapons & Classes
When a weapon appears in the Shop (35%), there is a chance to match an owned weapon, or an owned weapon's class (eg. Blade, Unarmed).
When the weapon appears, it is randomly chosen from one of the following three pools:
- Same Weapon Pool: 20% - Weapons of the same type as you already have equipped.
- Same Class Pool: 15% - Weapons that share one or more Weapons Classes with weapons you already have. (This can give you the same type weapons as you already have)
- All Weapons Pool: 65% - All Weapons in the game that are possible.
This means that weapon classes with fewer weapons give you a higher chance to find the weapon you're using.
The shops for waves 1-5 also have a bonus chance for the same weapon class. The bonus is higher for earlier waves.
| Shop(Wave) | 1 | 2 | 3 | 4 | 5 | ... | 6 - 20 |
|---|---|---|---|---|---|---|---|
| % Bonus | 12.5 | 10 | 7.5 | 5 | 2.5 | ... | - |
| % Bonus + Base (15%) | 27.5 | 25 | 22.5 | 20 | 17.5 | ... | 15 |
This bonus allows for a build selection in early game, since the first 2 shops guarantee two weapons, and the next 3 shops guarantee at least one weapon.
Modifiers
Item Cost
Coupon reduces shop prices by -5%, and is the only item that can do this. Shop cost reductions stack additively and the total can be seen in the secondary stats tab. The maximum cost reduction you can have is currently 50% by playing Entrepreneur and having the maximum amount of 5 coupons.
Waves
Harder waves give better shops.
Specifically, each new wave increases the chance for rarer items, as shown in Rarity of Shop Items and Luck above (see "current wave" in the calculations).
Character Specific
Bull is the only character that will not get offered a weapon since it cannot use weapons. It will only get offered items.
Demon is a unique character that buys items with 
Max HP.- Entrepreneur has -25% Items Price buff.
Saver and Mutant have +50% Items Price debuff.
Glutton has +25% Items Price debuff.
Ranger Can only purchase Range weapons in the shop.
Gladiator Can only purchase melee weapons in the shop.
Knight Can only purchase melee weapons in the shop, and all weapons offered are Tier 2 or higher.