Gene Tonics are special serums made from processed ADAM that introduce modified stem cells into the body, allowing for genetic modification and mutation, giving the user what some might call "super powers". In BioShock 2 Multiplayer, the player is able to choose from a selection of up to seventeen Tonics, and equip three of them per loadout. Even though Tonics have three classifications (combat, physical, and engineering), they can be mixed in any number from any classification up to the maximum. Rather than being purchased or found, Tonics are automatically rewarded after reaching a certain Rank.