EVE Saver is a Gene Tonic available in BioShock, BioShock 2 and the BioShock 2 Multiplayer. When equipped, it reduces the amount of EVE consumed when casting Plasmids. In BioShock 2, EVE Saver reduces the EVE cost of Plasmids by 10%, while EVE Saver 2 reduces it by 15%. Stacking both versions will reduce the cost by around 24%.
In Worlds of Hurt, EVE Saver can be bought at the Gatherer's Garden in the central hub for 20 ADAM.