Infusions are used to upgrade your Health, Shield, or Salts. Depending on your play style and difficulty setting, they can be imperative to stay alive in Columbia.
Infusion #7 – (Soldier’s Field)
In the hidden compartment of the Fellow Traveler restaurant. To unlock the area, find the code book in the cannon of the Tickets building. Take it to the Vox Populi code in a bathroom in the Fellow Traveler. Then use the nearby hat rack to unlock the secret area. For a more in-depth explanation, use the Vox Populi Code Guide.
Infusion #8 – (Hall of Heroes)
One of the first areas in the Hall of Heroes is a large room with a statue of Comstock and other defaced statues. Slate sends some soldiers your way from a storage room, where this Infusion waits.
Infusion #9 – (Hall of Heroes)
After reaching the Hall of Heroes Gift Shop and finding that all of the Shock Jockey bottles have been used, go back to the previous area where Elizabeth can open tears. Slate will start a battle and unlock a door on the first floor with an electric blast. Inside the room is an Infusion and Voxophone #32.
Infusion #11 - (Beggar’s Wharf)
After Elizabeth runs away from you and gets captured by the Columbia Authority, save her and pick up this Infusion on the first floor of the building where she was held captive.
Infusion #14 - (Plaza of Zeal)
After finding the Code Book in the Good Time Club basement, take it to the clock shop in the Plaza of Zeal. Then, interact with the clock next to the Vox writing to move it out of the way and reveal the Infusion and Voxophone #41.
Infusion #19 - (Port Prosperity)
In the locked area of the room with the scalps pinned to the board. The door requires three lock picks to be unlocked.
Infusion #20 - (Emporia)
In the locked room of the Salty Oyster. To unlock the door, find Voxophone #56 “Sally” in the basement of Founder’s Books. It says a button under the Salty Oyster’s cash register will open the door.
Infusion #23 - (Memorial Gardens)
Hidden in the secret area of The Bank of the Prophet along with Voxophone #66. First, go to Hudson’s in between the Market District and the Financial District. A Code Book is in the basement of Hudson’s near a sink. Take the code book to The Bank of the Prophet. Facing the vault door, take the left path in the teller area to find the word “Hoarder” painted on the wall. The code and a type writer are on a desk nearby. Elizabeth translates it to, “Type three letters to spell the voice.” Interact with the type writer to make the nearby cabinet move. For a more in-depth explanation, use the Vox Populi Code Guide.
Infusion #24 - (The Operating Theater)
After rescuing Elizabeth from the operating table, take her to the room overlooking the operating area where Comstock addressed you to find this Infusion and Voxophone #76. Three lock picks are needed to open the door.