The Killinder tends to move back and forth across the elevator shaft in a rising and falling pattern.
- Fires six bullets in the direction of the player, one for each of its chambers.
- Releases a ring of bullets around itself.
- Moves to the center of the elevator shaft, and creates six clones of itself around the shaft, mimicking the structure of a cylinder. These clones each fire a large projectile towards the main Killinder one at a time in a clockwise formation. When these projectiles are fired, the clones vanish, and upon the projectiles hitting the central Killinder, the central Killinder will fire a collection of smaller bullets in the player's direction.
- Moves back and forth across the top of the screen, spitting fiery bullets that are affected by gravity, and fall down towards the platform below. It also released a ring of bullets from itself occasionally while performing this attack.
- Fires a spinning ring of six bullets that lazily homes in on the player.
- Moves in rapid, wide circles while firing wide spreads of bullets outwards from itself.
- Moves to the center of the elevator shaft and creates six clones of itself that sit very near to the original, before beginning to rotate around it. The Killinder then releases several spiraling lines of bullets around itself. It also occasionally also releases a ring of bullets around itself while performing this attack.
- Killinder as a boss is completely unique to Exit the Gungeon, having made no appearance in Enter the Gungeon.
- Upon the Killinder's death, it is revealed that it is not entirely fire, as a metallic skeleton can then be seen.
- In early versions of the game, the Killinder was known as the 'Flamechamber'.
- According to the description it is a reference to the loading icon that occurs when passing through floors in Enter The Gungeon.