. They're located at the very top underneath where you buy plasmid slots. You should be able to purchase it at the second gatherers garden:) Upvote. Click to expand then you are able to buy. extra objectives and it took me at least 25 hours. They're located at the very top underneath where you buy plasmid slots. Plasmid Slots are purchased at Gatherer's Garden machines throughout Rapture for ADAM each. You can buy either of two kinds of ability slots -- plasmid (special power) or tonic (passive ability) --that allow you to use many talents simultaneously. Comprar los 3: $00$ Comprados juntos In Bioshock 2, you have numerous tonic slots/plasmid slots, etc. If you don't. The price does not change during the game. You can also only buy a maximum of twelve tonic slots throughout the. You can also only buy a maximum of twelve tonic slots throughout the game. Tonics are so varied that it's pretty much. That's at least 4 plasmid slots, since you start with 2 you'll need to buy at least 2 more. The 2nd area - Neptunes Bounty has a Gatherer's Garden where you can buy an extra plasmid slot.