Master Protector is a Gene Tonic in the Minerva's Den DLC for BioShock 2. It increases harvest times for any Little Sister protected by the user, thereby increasing the amount of ADAM she can collect by 40.
Considering there are only a few Little Sisters in the DLC, this Tonic should come in handy. However, it nearly doubles the duration of a gathering session, and hence provides extra challenges to the player. On higher difficulties, equipping this Tonic may result in the player running low on all other resources.