A character might drink one potion while still under the effects of another, or pour several potions into a single container. The strange ingredients used in creating potions can result in unpredictable interactions.
When a character mixes two potions together, you can roll on the Potion Miscibility table. If more than two are combined, roll again for each subsequent potion, combining the results. Unless the effects are immediately obvious, reveal them only when they become evident.
d100 = 5
The mixture becomes an ingested poison of the DM’s choice.
|1||The mixture creates a magical explosion, dealing 6d10 force damage to the mixer and 1d10 force damage to each creature within 5 feet of the mixer.|
|2-8||The mixture becomes an ingested poison of the DM’s choice.|
|9-15||Both potions lose their effects.|
|16-25||One potion loses its effect.|
|26-35||Both potions work, but with their numerical effects and durations halved. A potion has no effect if it can’t be halved in this way.|
|36-90||Both potions work normally.|
|91-99||The numerical effects and duration of one potion are doubled. If neither potion has anything to double in this way, they work normally.|
|00||Only one potion works, but its effect is permanent. Choose the simplest effect to make permanent, or the one that seems the most fun. For example, a potion of healing might increase the drinker’s hit point maximum by 4, or oil of etherealness might permanently trap the user in the Ethereal Plane. At your discretion, an appropriate spell, such as dispel magic or remove curse, might end this lasting effect.|