Slinger begins the fight by falling down from the ceiling and face-planting, releasing a burst of blood projectiles, a small pool of red creep, and lodging a Toothache tooth into the ground.
The tooth will constantly leak damaging red creep if left alive, but can be destroyed at any point.
While idle, Slinger paces slowly after Isaac with a thread attaching his head to the ceiling, and will choose to perform the following attacks at random:
Throws his head at Isaac which bursts upon colliding with a wall or with Isaac, releasing a Spider, Level 2 Spider, and a swarm of Baby Spiders, as well as leaving behind a Cobweb. After this, Slinger will grow a new head.
His head can be damaged while in the air, and if it is killed before it reaches the wall it will not spawn any spiders.
Spins around, releasing 4 rotating streams of projectiles in a spiral pattern before getting dizzy and faceplanting, releasing a burst of blood projectiles and leaving a small pool of red creep underneath himself.
Sometimes while spinning Slinger will tangle himself up in webbing, and raise into the air slightly.
While in this state Slinger's projectiles gain extra range, and he can no longer be collided with, including by tears and other weapons.
Occasionally after tangling himself up, he will swing back and forth in the air, periodically spitting out either a Spider or white Oralid towards Isaac. He will fall back down after spitting out 7 spiders.
Slinger has a higher chance to perform this attack if below 50% health.
Attaches two strings of webs to the ground directly to the left and right of him before yanking upwards, creating a spray of rock projectiles and spawning 2 Creepy Maggots.
Slings out two strings of webs that attach to the walls left and right of him, before yanking them and causing a spread of rock projectiles to fly inwards. In the middle of both sprays is a larger rock projectile that travels further than the rest, when these two projectiles collide they will each split into a 3-way scattershot.
Slinger was originally a part of the cancelled Morbus MOD.
In his Morbus incarnation, he pulled Foetu from the walls and Toma Chunks from the ground.
Despite being a popular misconception, Slinger was not designed to look like Bertran, a popular character MOD, as Slinger was first designed about 3 weeks before Bertran was ever revealed.
Slinger's "thumbs up" gesture and the broken-toothed smile he makes is a reference to the similar iconic pose made by Meat Boy, protagonist of the game Super Meat Boy.
Catacombs.
Toothache tooth into the ground.
Spider, 
Level 2 Spider, and a swarm of 
Baby Spiders, as well as leaving behind a 
Cobweb. After this, Slinger will grow a new head.
Oralid towards Isaac. He will fall back down after spitting out 7 spiders.
Creepy Maggots.
Skuzz, 
Small Skuzzball, and a swarm of 
Soot Tag instead of a Cobweb.
Chargers out of the ground instead of 
Foetu from the walls and 
Toma Chunks from the ground.
Bosses 