In Valor Mortis, your Ferrofluid Flasks are what keep you alive. These healing items are your main way to recover health mid-fight, and they refill to your maximum each time you rest at a Lantern. You start the game with only 3, which doesn’t leave much room for error. That’s where Empty Ferrofluid Flasks come in.
Empty Ferrofluid Flasks are an upgrade material that raises the number of Ferrofluid Flasks you can carry. There are 9 in the game. Each upgrade uses one Empty Ferrofluid Flask. To use one, rest at any Lantern and open the Upgrade Ferrofluid Flasks menu. Collect all five and you’ll go from 3 flasks to 12, more than double what you started with. Some are hidden off the main path and easy to miss, so it’s worth tracking down every one.
This guide lists the location of every Empty Ferrofluid Flask, so you can raise your healing capacity as early as possible and go into tough fights better prepared.
Empty Ferrofluid Flask 1
The first Empty Ferrofluid Flask can be found in the red chest directly to the left of "The Climb" Lantern in the Valley of Ashes region.
Empty Ferrofluid Flask 2
Starting at the "Marketplace" Lantern in the Fallen Village region, use the Grappling ability on the blue hooks to swing across the river to reach the fire area, continue on this path until you see a house on your right near a wooden wagon.
The chest containing the Empty Ferrofluid Flask is in front of this house by the wagon.
Empty Ferrofluid Flask 3
For the 3rd Empty Ferrofluid Flask, start at the "Old Mine" Lantern in the Caverns region and take the main path down to the right, when you reach the wooden stairs go all the way to the top where you will find a lever.
Pull the lever to raise the platform then use the Stasis Transmutation to freeze the cogs in place to keep the platform raised.
Jump across the platform and once you enter the next cave, take the first path that you see on your left, here you will see a rotating platform that you can also freeze by using the Stasis Transmutation again allowing you to cross over to the other side.
Empty Ferrofluid Flask 4
From the "Ship Graveyard" Lantern in the Vale of Wrath region, turn around and backtrack to the small camp you cleared out just before reaching this checkpoint, the chest containing the Empty Ferrofluid Flask is in the middle of this camp.
Empty Ferrofluid Flask 5
The 5th Empty Ferrofluid Flask can be found just the other side of the shortcut near the end of the level that takes you back to the "Village Church" Lantern in the Cursed Hollow Region.
Empty Ferrofluid Flask 6
Inside the building near the "Market Square" Lantern (in The Outskirts region) that you had to blow up the barrels in to open the shortcut back to the Lantern.
Once inside the building, go up the stairs on the left to where the tall enemy is looking out the window and turn around 180º at the top of the stairs to be able to jump across to the top floor where you will find the Upgrade in the chest on the left (be careful as the chest will explode when you open it).
Empty Ferrofluid Flask 7
The 7th Empty Ferrofluid Flask can be found in the University region, starting at the "Main Hall" Lantern, go up the stairs to the right of the big statue and go through the only door that will be open the first time you visit this area.
In the first hallway, go straight ahead and jump across to the other side by swinging on the purple pole, as soon as you swing across go to the right to reach a balcony area, here go to the left until you reach the end of the hallway, then take another left, continue on this path until you reach 2 sets of big stairs.
Walk past the 1st set of stairs and go up the 2nd set of stairs (the ones with the hole at the top that you can crawl through). Through this hole you will find a red orb you need to destroy that will reveal a lever that you can pull.
Activate this lever to move the statue in the area below revealing the chest that contains the next Empty Ferrofluid Flask.
Empty Ferrofluid Flask 8
Starting from the "Courtyard" Lantern in the Fortress region, go into the main building on the left that has the big long hall.
Inside go all the way to the right where you will see the Eternal Guards symbol on the wall next to a hidden door.
To be able to interact with the symbol you need to have all the Stone Pyramid pieces (dropped by the Eternal Guards mini-bosses), once you have all of them, they will combine into the Stone Slab which you can use to interact with the Symbol to access the secret room, where the Upgrade can be found in the chest on the left.
Empty Ferrofluid Flask 9
The final Empty Ferrofluid Flask is sold in the "Abandoned Church" at Louis's Laboratoire workbench for 3,000 Catalysts.
