Hosts
Hosts are enemies which hide inside protective skulls, only becoming vulnerable to damage when they lift their skull to attack Isaac.
This page is about Hosts added by Fiend Folio. More information about Hosts in general can be found in the vanilla page.
For the baby version of these enemies in Fiend Folio, see 
Smidgen.
Eroded Host
Eroded Hosts are a variant of Hosts which appear in the 
Flooded Caves and behave similarly to their counterparts, but have weaker shells that can be damaged while it is hiding. When Isaac is in range, an Eroded Host will open up and launch a volley of arcing projectiles towards him that trails after his movement. If it is damaged while exposed, it will retreat into its skull quickly, interrupting the attack.
If an Eroded Host's skull takes 15 damage, it will crack and the Eroded Host's projectiles will increase in number and size, while also greatly lowering the cooldown between its attacks.
After another 10 damage is dealt to an Eroded Host's skull, it will break entirely, causing it to be vulnerable at all times similar to a 
Red Host. In this state, the cooldown between attacks is reduced further, and its volley of projectiles becomes more dangerous: the projectiles will be greater in number and become less accurate, will cover a larger area, and the Eroded Host will launch an additional cluster of projectiles at the end of the volley. Eroded Hosts in this state will no longer cancel its attack to retreat when taking damage.
Eroded Hosts are most commonly encountered in their first stage, but can be encountered with any level of erosion.
Notes
- Explosions will instantly crack an Eroded Host's shell by one level.
- Hitting an Eroded Host's shell with a
Sulfuric Acid tear will instantly crack it by one level.
G. Host
G. Hosts are a ghostly version of Hosts found in the 
Depths, which will remain stationary and will never attack directly. Periodically, a G. Host's eyes will dim, and a G. Host Spirit will appear somewhere in the room close to Isaac and shoot a spread of 3 spectral projectiles towards him that can deal a full heart of damage. Afterwards, the G. Host Spirit will attempt to slowly float back towards the respective G. Host skull that spawned them and enter it, causing the skull's eyes to light up again.
Only a G. Host's spirit is vulnerable to damage, and once it dies, their corresponding skull will die alongside it.
Sludge Host
Sludge Hosts are a variant of Hosts found in the 
Dank Depths. They constantly emit a small pool of black creep around themselves, and when attacking, Sludge Hosts release an inaccurate volley of projectiles that leave black creep where they land, along with spitting out 2 
Blots in a V pattern. When retreating back into their skull after this attack, Sludge Hosts will scatter additional projectiles in random directions.
Bola
Bolas are a variant of Hosts found in 
Utero. When Isaac draws close, their head drifts away from their body towards Isaac, attached by a cord similar to that of a 
Swinger. While their head is detached, their body will be exposed and vulnerable to damage.
The head itself is invulnerable and will slowly move towards Isaac, while being restricted from moving a certain distance from its body by its chain. During this time, a boil will begin to swell in the head's eye socket before popping, releasing a disorganized cluster of projectiles towards Isaac. The head will continue to do this until Isaac moves out of its range, where the head's boil will stop swelling and the head will retract back to its body, protecting it from damage until the head detaches once again.
Mold
Mold are variants of Hosts that only appear inside of Crawl Spaces. Molds are able to hang onto walls or ceilings of the Crawl Space, and when Isaac draws within range, they will fire a straight stream of 4 projectiles at him.
Trivia
- Like normal Hosts, Sludge Hosts and Molds will play a special animation if damaged enough while they are hiding in their skulls.
- Smidgens appear to be tiny versions of Hosts, and come in several variants.
Hosters are a fusion between a Host and a 
Slammer.
Jammed and 
Red Jammed spawn 
Hostlets and 
Red Hostlets respectively ― a smaller version of Hosts, yet larger than Smidgens.- The design of G. Hosts was modeled after
Gutbusters. - Bolas are named after a type of weapon which consists of two weights attached together by a chain.
- Molds appear to be fusions of Hosts and
Haunches, with their vulnerable parts being made of a similar material as the latter.
Gallery
All three stages of a Eroded Host while closed.
A Sludge Host's appearance while closed.
A G. Host skull when its spirit is out.
A G. Host Spirit.
A Bola's appearance while closed.
A Bola's different stages before firing projectiles.
A Mold's appearance when closed.
Old version of Eroded Host.
Concept art of G. Host.
