When used, Isaac will hold Kalu's Severed Head above him, and a dark cone of vision with limited range will appear when holding one of the shooting buttons in that direction, and can be aimed in any direction within 360° around Isaac.
The cone of vision petrifies enemies and deals 2% of Isaac's damage every 5 ticks (or 12% every second) to enemies inside the cone. If an enemy that has been petrified by the cone dies, they will burst into a ring of 8 tears which inherit Isaac's damage and tear effects.
Holding the shoot buttons will gradually deplete the charge bar, with a maximum duration of 1.5 seconds to fully discharge it. When the shoot buttons are let go, when the item itself is manually activated again, Isaac will put down the head, which will cancel the use of the Item without fully discharging it. The charge bar will begin recharging while Kalu's Severed Head not in use.
Notes
Kalu's Severed Head, like most active items with a timed recharge, can only be used once fully charged.
The cone of vision has a set range, and cannot be modified by any of Isaac's stats or held items.
Enemies petrified by the cone of vision will stay petrified for a short duration when they leave the cone, with the duration scaling with how long the enemy was inside the cone.
Bosses and mini-bosses that make contact with the cone of vision will always be petrified for 4 seconds, no matter how long they've been in the cone. The petrification can end even while they're inside the cone, and are temporarily immune to petrification for a short while after.
Interactions
The Battery: Allows the Item to have two charges to store, effectively doubling the maximum usage time to 3 seconds — while also needing 20 seconds to fully charge both bars once fully depleted.
Car Battery: The duration of the petrification and the damage dealt by the cone of vision is doubled. No effect on the tear burst created when a petrified enemy dies.
Abyss: Absorbing Kalu's Severed Head spawns a white Abyss Locust that deals 10% of Isaac's damage and petrifies enemies they hit for 2 seconds. These enemies won't burst into tears when killed while petrified, however.
Eternal Car Battery: On use, damage and duration of the petrification is multiplied by a random amount between 3-5 times. If Kalu's Severed Head is deleted, the head will still be able to create a cone of vision for up to 10 seconds, or once it stops being used.
Video Showcase
Trivia
Kalu's Severed Head is based on Fiend Foliodeveloper JonTheRealJon's dog Kalu, who Jon was known to post about on their Twitter under #mydogkalu describing them as if they were some ineffable, abominable entity.
The Battery: Allows the Item to have two charges to store, effectively doubling the maximum usage time to 3 seconds — while also needing 20 seconds to fully charge both bars once fully depleted.
9 Volt: No effect on the Item's recharge time.
Car Battery: The duration of the petrification and the damage dealt by the cone of vision is doubled. No effect on the tear burst created when a petrified enemy dies.
Abyss: Absorbing Kalu's Severed Head spawns a white Abyss Locust that deals 10% of Isaac's damage and petrifies enemies they hit for 2 seconds. These enemies won't burst into tears when killed while petrified, however.
Eternal Car Battery: On use, damage and duration of the petrification is multiplied by a random amount between 3-5 times. If Kalu's Severed Head is deleted, the head will still be able to create a cone of vision for up to 10 seconds, or once it stops being used.
