Killroys Slaughterhouse is a set of challenges in World 2 which reward you with skulls to buy various items with from the Skull Shop.
While the rewards are nothing game-changing, it’s a nice free bonus to get each week and this guide will go through how it works and what you should be spending your Skulls on.
Also with the addition of Killroy Prime in the Rift, you can now get a nice damage boost and new upgrades like higher artifact find chance for Sailing.
How Killroy Works
When you enter World 2, you will definitely notice Killroy and his pile of skulls next to the alchemy cauldron.
Once you click on him, you have two options to choose from, Enter Fight or Skull Shop.
The Fight section has up to three rooms to complete (you start off with one Room per week, but unlock the another one when you reach World 4 and the third one you can buy from the Skull Shop once you get Killroy Prime from the Rift), each of which have a randomized class requirement. This means you can only complete that room with the archer, warrior or mage class that the image specifies.
The monsters you must fight are also randomized, they can be from any world that you have reached.
No choice!
There is no way to select which rooms or classes you get each week, so you will just have to deal with what you get. Try to get your class-advancements as fast as possible, as their stronger skills will help clear these rooms more efficiently.
Once the fight begins, you will see a timer and a kill counter at the top of the screen and your only goal is to get as many kills as possible before the timer runs out.
The actual kill counter doesn’t actually have any effect on rewards, but enemies have a chance to drop skulls on death, which can then be used to buy various items from the Skull Shop.
Sometimes they can also drop Talent Points for your skill tabs, but there seems to be an ambiguous limit on the amount, as they will stop dropping later on.
Once the timer runs out, you get to choose one of six permanent upgrades, explained in the next section.
Which Upgrades to Choose?
As mentioned above, there are six different upgrades that you get to choose from after each run.
However they are not created equal, as the timer upgrade is by far the most useful one, where you should be putting most of your points into.
| Upgrade | Description |
|---|---|
 | Adds +1 second to the room timer. The timer starts at 100 seconds. This is the best upgrade! |
 | Get more talent point drops from Killroy battles, drops off fast, don’t put many points here. |
 | More skulls dropped from a Killroy run. Also doesn’t scale well, so put less points here than the timer. Around 90% into timer and 10% here. Some people put everything purely into timer. |
 | Faster respawn for Killroy mobs. Again not great scaling so put only a few points here. |
 | Killroy mobs can drop Dungeon Credits. Not worth putting points into, as Party Dungeons give enough on their own. |
 | Killroy mobs can drop pearls. Also not a great investment for points, could put a few here just to start getting a few pearls. |
The Bonus Skulls upgrade is slightly misleading, as it says +1% per level, but the amount really degrades fast after 20-30 points, so you won’t notice much difference after that.
This means, towards the end, it won’t make much of a difference which one you upgrade, but upgrading the timer is the best option if you have the patience to wait it out every time.
Best items to buy from the Skull Shop
The Skull Shop has a lot of variety, but some are definitely worth more than others. A lot of the ‘best’ choices depend on what stage you are at in the game and what you need more progress on.
We made a table showcasing the value of each item in the shop and added a reason when or why that item might or might not be worth buying.
| Item | Description | When to buy | Value |
|---|---|---|---|
 Time Candy | 1 Hour Time Candy (45% chance) 2 Hour Time Candy (50% chance) 4 Hour Time Candy (5% chance) | If you need candy for faster progression early on. |  |
 Black Pearl | Gain +20% XP on current Skill if it’s under level 30 | If you need help with Maestro progression. Time Candy also works for this purpose though. |  |
 Holy Pearl | Gain Class EXP | This has been upgraded recently to work well on high levels too, so not as bad as it used to be. If you need fast talent points, feel free to buy a few. | |
 Crystal Mob | Next kill spawns a Crystal Mob | Can be useful for a few quests or leveling up Crystal Cards. This often bugs out and you get nothing! |  |
 Dungeon Loot Dice | Get a single Dice, as you would from a Party Dungeon | Might get a keychain, depending on roll. Not worth it unless you really struggle with Party Dungeons. |  |
 Arcade Balls | Get 6 Arcade Balls | This is now pretty good as Arcade was updated to double the effect of a bonus after level 100. |  |
 Library Checkouts | Get 2 Library Checkouts | One of the best items to buy if you haven’t maxed out most of your talents already. | |
 Refinery Cycle | Completes 1 Refinery Cycle | Salts are slow, so this will definitely boost your progress fast. | |
 Pet Eggs | Get 2 Pet Eggs | Expensive, but good source of Eggs if you need fast pet progression or upgrade materials. | |
 Cooking Ladles | Get 3 Cooking Ladles | Can help very early on to speed up cooking, but later on it’s not worth it. | |
 Weekly Fight (from Rift) | 1% chance to gain a third Weekly Killroy Fight (Can’t get more than 1!) | This is the best upgrade to buy until you unlock the third fight! After you get it, don’t put more points here, they do nothing! |  |
 Sailing Artifact Find (from Rift) | Boosts Artifact Find Chance | Not a huge boost, but useful if you are still missing a lot of artifacts. Check out our Sailing guide if you want to find out more. | |
 Gaming Golden Nugget (from Rift) | Adds 1 nugget to your shovel in Gaming | Not useful, leveling up gaming is very fast and gets boosted by many other means. |  |
 Crop Evolution (from Rift) | Increases Crop Evolution chance in Farming | Decent multiplier if you’re missing a lot of crops. | |
 Jade Gain (from Rift) | Increases Jade Gain in Sneaking | Similar to crop evolution, if you are struggling with Sneaking, level this one up. | |
The last 5 entries in the table are unlocked through the Rift’s Killroy Prime reward.
The Library Checkouts also help you reach the World 3 Achievement called Checkout Takeout which requires you to checkout 1,000 talent books from the Library, but it is extremely useful as it gives +5 Max Level to all books and +30% faster library charge rate.
However, if you haven’t reached World 5 and Sailing yet, your book Max Levels will increase greatly from there, so you will need to max out more talents again, so you might want to wait until then and spend the Skulls on World 4 boosts meanwhile.
The Refinery Cycle is always useful as most important crafting recipes need Salts and they can be very slow to gain before you have leveled your Refinery up.
Finally, when it comes to Cooking Ladles, they will help out with cooking early recipes, but once you get high Cooking Efficiency later in the game, you will easily get hundreds of ladles per day on a Warrior class.
Spending Gems to wake up Killroy
It is possible to spend 300 Gems to wake up Killroy once a week, so you get 2 extra rooms to play through for that week, also meaning 2 extra upgrades and more Skulls.
When you reset Killroy, the rooms are not randomized, they’re simply reset.
However, 300 Gems is a steep price for just a few Skulls and there are certainly better things to spend them on in the Gem Shop, so unless you’re a high spender and have everything unlocked from the Gem Shop already, don’t bother.
Especially don’t do it if you don’t have 2 Rooms unlocked yet, aka you haven’t reached World 4 yet.