Potions

Description
Potions can be used to instantaneously regenerate a percentage of a resource. The amount restored is a percentage of your max capacity. There are potions for Mana, Slime, Darkness, and all 3 resources at once. Potions can be merged into higher levels.

Note: A level 3 Darkness potion will over-fill your capacity, so it is better to use one level 2 potion, spend some darkness, then use the other level 2 potion.

All
100% for all resources

Source
A cauldron holds several potions at once, and they can also be bought in the shop.

The potion to fill all resources at once is only available in bundles from the shop.