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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, when you buy a Dangerous Bunny in a shop, it reduces the cost of the current reroll, instead of granting a "free rerolL".
| Wave | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Base Reroll Price | N/A | 2 | 3 | 4 | 6 | 7 | 9 | 10 | 12 | 13 | 15 | 16 | 18 | 19 | 21 | 22 | 24 | 25 | 27 | 28 |
| Price Increase per Reroll | N/A | 1 | 1 | 1 | 2 | 2 | 3 | 3 | 4 | 4 | 5 | 5 | 6 | 6 | 7 | 7 | 8 | 8 | 9 | 9 |
To understand the above table, take for example, on Wave 11 the first reroll costs 15. And each subsequent reroll costs +5. So it goes 15, 20, 25, etc.
Locking
You can lock as many items as you can which ensures your next shop will keep those items of your choice. This is very useful when you can't currently afford an item, or if you want to wait with buying an item. It is free to lock and unlock items and you can do it as much as you want.
When you lock an item, it does change or go away when you reroll the shop and it stays there until the next shop if you go to the next wave. Locked items' price doesn't change or inflate if you keep it between shops.
Combining
If you have two identical weapons eqiupped, 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
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.
Inflation and shop prices.
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: Inflated price = Base price + (10% of Base price + 1) • Shop number.
So if an item has a base price of 90 and you see it in the first shop, it will cost 90 + (9 + 1) • 1 = 100 gold. And its price will increase by 10 gold for each wave/shop that passes.
Since the Equation includes a flat +1 in 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. Notice that the first shop you encounter is Shop(Wave 2).
Available From Shop(Wave) tells you the first shop number where you can encounter the rarity.
| Available From Shop(Wave) | Min Shop(Wave) | Base Chance | +Chance per Wave | Max Chance | |
|---|---|---|---|---|---|
| Tier 1 | 2 | 2 | 100% | 0% | 100% |
| Tier 2 | 3 | 2 | 0% | 6% | 60% |
| Tier 3 | 5 | 4 | 0% | 2% | 25% |
| Tier 4 | 9 | 8 | 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
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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% | 52% | 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 11 with 0 Luck, the chance for Tier 3 is 2*7 = 14% -- extrapolated: ( 2% * ( 10 - 3 ) + 0% ) * ( 100% + 0% )
- In wave 11 with 50 Luck, it increases by 50%, 2*10.5 = 21% -- extrapolated: ( 2% * ( 10 - 3 ) + 0% ) * ( 100% + 50% )
- In wave 11 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.
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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.
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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:
- Shop (Wave 2, 3): Guaranteed 2 Weapons + 2 Items.
- Shop (Wave 4, 5, 6): Guaranteed 1 Weapon + 3 other purchasables (ie. either a weapons or items).
- Shop (Wave 7+): 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 2-6 also have a bonus chance for the same weapon class. The bonus is higher for earlier waves.
| Shop(Wave) | 2 | 3 | 4 | 5 | 6 | ... | 7 - 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.