Fountain of Youth



Fountain of Youth is a Gene Tonic in BioShock 2. It causes the player to slowly regenerate health and EVE when in contact with water. This can be from standing under a large leak in the ceiling (flowing water that obscures the whole screen for a moment will heal you; dripping water is insufficient), standing in pools of water, or from being immersed in water while outside of Rapture.

Since plenty of water is around to stand in for filling up the Health and EVE bars, this tonic greatly reduces the cost of rebuying First Aid Kits or EVE or using the Health Stations. This also free up slots otherwise used by many other types of tonics related to regenerating health and EVE, which includes Booze Hound, Cure All, EVE Saver & 2, Extra Nutrition, and Hacker's Delight & 2, and being able to use those slots for more valuable tonics.

Strategy

 * A convenient way to refill is to stand in a pool of water after a battle and use Telekinesis to fetch and loot bodies, weapons, ammo boxes, etc., which you would otherwise be walking around looting.
 * Tapping the plasmid switch button constantly will delay the use of an EVE hypo, giving you time to reach water to restore EVE that way instead.


 * It's possible to use plasmids constantly and endlessly while in water with this tonic equipped, excluding the Level 3 elemental stream plasmids. This works because you will always gain a minor amount of EVE during the animation of a plasmid firing, and never trigger an automatic refill of EVE. Any plasmid can be used once as long as the EVE bar has any amount of EVE in it. The stream attacks, however, continuously drain EVE, at a rate faster than it is gained from water. Another benefit (or downside, if you seek a challenge) of doing this is that it will remove a significant amount of challenge from most parts of the game, even on hard, since pools of water can be found almost everywhere.


 * The above strategy of infinite plasmid use is great for defending Little Sisters while gathering or taking down Big Sisters and Big Daddies from a distance without using weapon ammo. Some great uses for Fountain of Youth are using Security Command 2 and 3 for free, permanant and easily replacable bodyguards/distractions, any level of Decoy, Hypnotize 2 and 3 for even more bodyguards/distractions, setting up and charging many Cyclone Traps quickly, constantly using Insect Swarm to damage and panic many enemies at once (from around corners or at least behind cover), repeated Electro Bolts for a constant stun while aiming for the head (or restoring health slowly if desperate) and/or using Incinerate! many times on single tough enemies for great damage.
 * Another use of the infinite plasmid strategy is to get easy research. While in water with Fountain of Youth equipped, use Electro Bolt regularly (between using other plasmids) to keep the enemy stunned in place then repeatedly use the non-damaging plasmids Security Command and Hypnotize on the enemy, then finish them as you wish. This can easily accumulate over 700 research points each time, sometimes even 1000. (Hurting an enemy or using Hypnotize will un-stun the target though, so be ready to quickly quitch back to Electro Bolt. Winter Blast can be used too, but will prevent some plasmids from being counted towards the research.)
 * One strategy involving the elemental stream attacks would be to equip Drill Specialist, EVE Saver 1 & 2. This will greatly reduce the amount of EVE drained by the elemental streams, and the constant restoration will slow the EVE considerably. Running out of EVE will still stop the stream anyway (and might trigger an EVE refill, but I'm not certain of that) so this is best used with a large amount of EVE to start with.


 * When using Scout, you will not restore Health and Eve based on where your real body is standing but where the "scout" of yourself is standing. This could be used to sneak past threats to heal yourself in a pinch.


 * Using this tonic with Natural Camoflage allows you to heal without worry of being ambushed in the process. You can even leave the game unpaused and do something else while healing.

Location
Received at Research level 4 of Spider Splicers.