Vis are enemies most commonly found in The Depths in groups of four to six, occasionally eight. When lined up with the player (horizontally or vertically), Vis will begin shaking violently and then fire a wide blood beam from their stomach for a few seconds.
Vis have the fastest kind of ranged attack in the game and requires constant attention to the Vis movements to avoid, so big groups can get very dangerous. To keep track of them, it can help standing on the center of a wall and dodge by moving towards a corner and then back or to the middle of the adjacent wall. In an open room layout, you can also try to move diagonally through the room to force them to attack. Then while they stand still firing, try to close in on and kill at least one of them as quickly as possible.
- The Vis' blood beam may still damage Isaac for a fraction of a second after the beam has disappeared, so be careful.
- Their attack is only triggered if there is no solid obstacle (e.g. a rock or a Stone Grimace) between it and Isaac. Use this to your advantage.
- If the player has Wrath of the Lamb installed, Vis may turn into Double Vis for a few frames when firing their blood beam.
- They appear to be a headless version of Gluttony, as both behave in the same way- Both try to align themselves with you in order to hit you with their blood beam attacks. The only difference between the two is that Vis cannot perform the 8-way shot that Gluttony can. They both look the same, except for the head.
- The Vis is a reference to the 'Vis Sisters' from Gish.
- Vis is Latin for Force/Power, and is the root of the word viscera, meaning internal organs.
Double Vis are a new enemy added with the Wrath of the Lamb DLC. They are similar to the regular Vis; however, they have blood around the openings and can shoot the beam from both sides, having a gash in its back similar to the one on its front. They are often found in Necropolis and Utero, and sometimes in the Catacombs.
Super Gluttony shares the same dual beam shot as well as the appearance of a Double Vis with a head.
- If you have Mom's Contacts and you petrify the Vis or Double Vis, the beam will stay up until the effect drops off the monster and it will return to normal.
Chubbers, like Double Vis, were added in the Wrath of the Lamb DLC. Instead of shooting the blood beam that regular vis and Double Vis have, Chubber shoots a little chubby similar to the Little Chubby Familiar, which can go through rocks. They can be found in the same locations as Double Vis; However, they are less common.
While their projectiles are more easy to dodge, they can be more of a distraction than their other counterparts and deal a full heart of damage instead. In addition, they usually seem to appear in larger numbers than other Vis and/or in rooms with less room to move around.
A Chubber is not considered dead until its Chub returns to where the Vis used to be and disappears. This Chub can still harm the player and will prevent the doors of a room from opening until it is destroyed.