Potion Loop

The **Potion Loop** is an end game strategy that allows players to push the game to its limits.

## Pre-requisites

In order to potion loop there are a two things that must be unlocked:

1. Rainbow Kernels must be unlocked
2. TRANSMUT3 in a Bottle must be unlocked

There are optional pre-requisites that can be unlocked to boost your chances of getting a loop:

* All-Potion
* TRANSMUT3
* Spirit
* Bottles in a Bottle

## How to Loop

The core of the loop is simply about transmuting potions into Rainbow Kernels in order to double the potions in the room to increase the chances of getting another Rainbow Kernels after transmuting.
There is a couple of things that will make a room easier to to loop in:

* The room you choose should have as many potions on the ground as possible.
* A room with a transmute already in it.

Technically a loop can be started in any room in the game, however due to the above criteria shops are the easiest room to set up a potion loop in.

Looping will also be significantly easier on a file with only the necessary items unlocked, while it is possible to loop on a save file with random potions, it will be more difficult to find pre-requisites to start a loop and will likely lead to getting a loop on a low level.

The basic procedure for looping is:

1. Gather any Rainbow Kernels and TRANSMUT3 in a Bottle
2. Find a room that you will use for looping, preferably a shop with four potions and a TRANSMUT3 station.
3. Start doubling all the potions on the ground as many times as you can, it is potentially worth doubling TRANSMUT3 in a Bottle once if you only have one, but make sure to not remove too many potions by doing this.
4. Transmute the potions until you find more Rainbow Kernels, and drink them when you find them to double the potions in the room again.
5. Watch your HP and the costs of the TRANSMUT3 stations, don't kill yourself and you do not want to be stuck without one. Antimatter can be very helpful for this step.
6. Repeat Steps 4 and 5 until you reach a critical point where you have stability in you loop, knowing when you can stop looping and start using potions is just something you get a feel for from practicing, there is no exact number of potions, however it doesn't hurt to have extras, usually its just a balance between how much time you want to spend on a run and how much risk you are willing to accept.

How to utilize the optional pre-requisites:

* All-Potion is very useful as it essentially doubles your chances of finding a Rainbow Kernels because it can be converted into one by drinking it. It can also be used for finding additional TRANSMUT3 in a Bottle or other utility potions.
* Spirit is a familiar that is very helpful for using this strategy, all three of its levels provide benefits that make it easier to start a loop:
	+ Level 1 ability adds an addition potion slot letting the character carry another potion.
	+ Level 2 ability additional potions from chests is helpful mainly if you move them to the room where you are loop, but it can also have a small chance of dropping a potion that is useful in a loop. This is useful in combination with Chest in a Bottle as well, you just have to be careful not to fill the room up with too many chests.
	+ Level 3 ability adds a chance to drop a potion when you drink one which is very useful for moving potions and getting potions on the ground because you will be drinking a lot of potions with this strategy.
* Bottles in a Bottle is a useful potion because it turns one potion into to, early on it can be useful because it can grow into many more potions with subsequent doublings.

## Using the loop

Now that you know the basics of setting up a loop its time to consider what to use the loop for.

Depending on the use case typically people using the potion loop will setup potions they want to duplicate in another room and use the first loop to gather more Rainbow Kernels to take into the other room and use, this can be difficult if you do not already have potions in another room or Bottles in a Bottle/Spirt/All Potion, so you can also hunt for potions in the room where you have your loop, it will just make most strategies consume more time.

### Blessings

The main way people tend to use the potion loop is to boost blessings. The blessing strategy uses 3 potions:

* Ambrosia is used to double a random blessing, this can be used multiple times to get blessings up to very high numbers.
* Holy Glaze is used to average your blessings, this will let you reduce blessing if they get to extremely large numbers, while simultaneously increasing blessings of lower levels.
* Altar in a Bottle This will give you an altar letting you add get another blessing that you might not have yet.

You can also use Blessed Blend, and Circle of Transmutation in place of an Altar in a Bottle, This will let you drop a Blessing on the ground, and the only way to transmute a blessing is with the Circle of Transmutation Potion

The main things to be careful of using this strategy is that your game can crash if you do damage greater than the 2.14 Billion integer limit, ie if you deal a single hit that does more than 214000000000 damage it will crash your game. This is something you need to be very careful of especially when it comes to crit damage, if you boost Ferocity and another one of the damage blessings (Strength, or Balance) then a good rule of thumb is to keep your blessings below 10000, this will be more than enough to one hit everything you encounter while staying well enough below the limit that you do not need to worry about getting a crash even factoring in variance of damage.

### Sho'guul

The potion loop is a handy way of increasing your chances of getting Sho'guul's lair, Its recommended to read on how the percentages work, but the short version is

* Minor Curses increase your chance by 5%
* Major Curses increase your chance by 10%
* Blessings decrease your chance by 5%

You can use Witch's Brew to generate lots of curses, you can only find this potion by opening cursed chest or bombing cursed torches, or the better option is to use the All-Potion to create one, you can duplicate it to get your curses up high enough to cancel out any blessings you've gotten in order to garuntee a Sho'guul's lair will show up. you can also bring more of these along so that after the percentage resets on the next floor you can garuntee another Sho'guul encounter, or just loop on every floor depending on how many times you want to see Sho'guul in a run.

The other important part of this strategy is getting rid of those curses, you should be able to find plenty of curse remove potions, or duplicate Talisman but the best strategy is to get a Purification Potion, just make sure to heal after you drink it.

### Relics

Using potions like Metamorphim, and Transmutagen will let you tailor your relics to be what you want them to be, or find relics you've never gotten before much like Transmutagen Blast.

Using the Shop in a Bottle, it is possible to obtain every relic in the game, excluding relics sold by Sho'guul.

### Thorium and Gold

Using Rainbow Kernels you can duplicate both gold and thorium, using it on thorium can quickly get you to the thorium cap of 999 helping to buy any blueprints you want to get. A faster way to get gold would be to use the blessing loop strategy to get alot of Wealth Blessings but this is an alternative.

## Common Pitfalls

Some things to be careful to avoid are

* Anything that lowers health significantly (Glass Cannon, Adventurer's Peril, Soul Guard, Poison Mushroom, Enfeebled, etc) as it will restrict the number of transmutes that can be done.
* Compulsion makes it impossible to save up potions for a loop or move potions in general
* Sweaty Palms can break potions in the room where you are transmuting and destroy the TRANSMUT3 station
* Diluting the potion pool with extra potions that you dont want or use. While you are forced to have all of the Initially Unlocked Items in the pool, minimizing unlocks with increase the chance of getting the potions you want.

## History

Looping in older versions used to be much easier as you used to be able to duplicate rainbow potions with Rainbow Kernels, meaning that if you had two Rainbow Kernels on the ground and drank one you could get an immediate loop of rainbow potions, this was changed in update 1.0.0 where the Rainbow Kernels and the All-Potion can no longer be duplicated with Rainbow Kernels, making the strategy more RNG based and thus harder to achieve.

This strategy was popularized on the discord by Priskip in mid April 2020. However it seems it was discovered by user 老皮历险记 with the earliest video proof of the strategy being used.

## References

1. ↑ evidence of the potion loop in an early version of undermine