Mister Mxyzptlk Red Brew can obtained from Pot O' Gold item vendors located in the JLA Watchtower and the Hall of Doom, next to Mister Mxyzptlk during the St. Patrick's Day event. The item can be purchased for 2 Lucky Tokens.
Vendor purchase Edit
Mister Mxyzptlk Red Brew is one of three consumables that must be used in order to earn the feat Drink Up!. Additionally, the consumption of this item contributes toward the feat Take One Down, Pass it Around. These feats are unique to the event and are required to earn the meta feat Pot of Gold.