Minecraft wiki entry for Before_1.9, associated text: This class of potions exist in the game code and are functional, but cannot be brewed. They are extended and empowered versions of existing potions, but the brewing process normally only allows for one of the two to take precedence. Thus, these potions result from custom data values that place both effects on the potion. The data values for these potions are essentially the values of the original potions added by 96 (e.g. the data value for Potion of Strength (8201) + 96 = 8297 (the data value of Potion of Strength II (extended))) See the table below for the complete set of what is included.