Pestilent Bloat

EntryNormalHard
Pestilent Bloat
Released	3 June 2021 (Update)
Members	Yes
Combat level	312
Size	5x5
Examine	An infinite mass of decay and death.
League region	Morytania✓
Combat info
Attribute	Undead
XP bonus	+22.5%
Max hit	8 (Flies); 40 (Stomp)
Aggressive	Yes
Poisonous	No
Attack style	Ranged
Attack speed	1 tick (0.6 seconds)
Combat stats
Aggressive stats
Melee defence
Magic defence
+600	No elemental weakness
Ranged defence
Immunities
Poison	Immune
Venom	Immune
	Open in DPS calculator
Advanced data
Monster ID	10812
Link	MOID

The Pestilent Bloat is the second encounter in the Theatre of Blood. It was created by a crazed vampyre known as "The Butcher" upon Verzik Vitur's request.

According to a book titled The butcher, the Bloat was created by using three giant heads, an ogre's corpse, four buckets of human blood, two cyclops arms, two catablepon legs, an apple pie, and a sense of pride.

Mechanics

The Bloat will walk around its room in a square as soon as the party enters the room. If any player is within its line of sight, the Bloat's flies will attack them, causing players to take rapid hits of 10-20 every tick until they are out of the Bloat's line of sight. This will spread to other players in the raid also and can therefore kill a party very quickly. Additionally, the Bloat receives 50% less damage (rounded down) while moving.

On the first walk after 39-47 game ticks (23.5 to 28.2 seconds), it will stop moving, allowing players to attack it and deal full damage. After 19.2 seconds, it will stomp the surrounding area, dealing 40-80 damage, though it can be tick eaten. After the stomp, it will stop moving after 34 to 42 ticks (20.4 to 25.2 seconds). If its Defence has been reduced, it will regenerate to full when it stomps. If a player is hit by a mutilated flesh, it will deal 30–50 damage and stun them temporarily. Falling flesh can be evaded beforehand by looking for their shadow on the floor, and will only occur when the boss walks around upon reaching 90% of its health in normal mode. If the Bloat turns or changes speed during the walk, Bloat cannot go down for 5 another ticks which can slightly extend the length of the walk if the turn or speed change occurs close to the end of the walking phase. Bloat can be eligible to turn every 32 ticks in regular mode.

Pestilent Bloat uses a custom implementation of the line of sight check for its attacks: rather than using one tile within the Bloat's 5x5 area as the reference point for these checks, all tiles on the side of the Bloat nearest to the player are checked for line of sight, and the attack is allowed to go through if any of them has an unobstructed view of the player.^[1]

The speed at which the Bloat moves depends on its health; up to 60.0%, it will always walk; between 40% and 60%, it will always run.

At 39.9% and lower, the Bloat will alternate between walking or running for every attack made on it regardless if it hits or not.

Hard Mode

In Hard Mode, in addition to the previous mechanics, mutilated flesh will fall from the ceiling all of the time; starting as soon as the first player enters the room. It will continue to fall even when Bloat has stopped.

The Bloat is also more likely to change direction whilst moving, and can do so multiple times per rotation. Unlike regular mode, it is eligible to turn every 16 ticks in hard mode.

Entry Mode

In Entry Mode, Bloat can scale down to 20% of its original Hitpoints when done in a solo party. The encounter is generally less punishing for mistakes due to its lower damage from flies and the stomp. This allows players the freedom to practice against the Theatre of Blood bosses without as much risk.

If a team wipes in Entry Mode, they will be taken back outside of the boss room and have unlimited attempts to fight the boss again. Hardcore ironmen will still lose their status upon death.

Drops

	Item	Quantity	Rarity	Price	High Alch
	The butcher	1	Always; Never^{[d 1]}	Not sold	30

^ No longer dropped after reading the book.

Changes

Date	Changes
3 June 2021 (Update \| poll)	Hard mode and entry mode versions of the Theatre of Blood encounters added.
21 June 2018 (Update)	The falling flesh attack now falls another one tick slower and the shadows increase in size as they approach the ground.
8 June 2018	Hotfix The falling flesh attack now falls one tick slower to make them easier to dodge.^[2]

Trivia

Prior to the addition of Nex, which came with under-the-hood game engine changes that allowed for proper running for NPCs, the Pestilent Bloat was one of the only NPCs (excluding some that only appear in cutscenes) capable of moving at a running speed, due to having a fixed path.^[3]
The Pestilent Bloat had a festive override wearing a red partyhat during the 2018 and 2019 Christmas events. For the 2023, 2024, and 2025 Christmas events, the Bloat had a santa hat instead.

References

^ Jagex. Mod Ash's Twitter account. 8 November 2023. Archived from the original on 8 November 2023. Mod Ash: "It is line-of-sight as far as I can see in my colleagues' code, but that boss has custom line-of-sight checks. (...) The developer appears to have tried writing a manual check to see if any tile on the NPC's nearest side has line-of-sight to the target. The standard line-of-sight checks apparently aren't reliable for this for large NPCs."
^ Jagex. Old School RuneScape's Twitter account. 8 June 2018. Archived from the original on 30 May 2020. Old School RuneScape: "We've just hotfixed the falling body parts during the Pestilent Bloat encounter so they will now fall a little slower."
^ Jagex. Mod Ash's Twitter account. 17 September 2019. Archived from the original on 30 May 2020. Mod Ash: "The Bloat and certain cutscene NPCs have a hack to pretend they're running, but that only works for pre-defined paths"

[book-2] No longer dropped after reading the book.

[1] Jagex. Mod Ash's Twitter account. 8 November 2023. Archived from the original on 8 November 2023. Mod Ash: "It is line-of-sight as far as I can see in my colleagues' code, but that boss has custom line-of-sight checks. (...) The developer appears to have tried writing a manual check to see if any tile on the NPC's nearest side has line-of-sight to the target. The standard line-of-sight checks apparently aren't reliable for this for large NPCs."

[3] Jagex. Old School RuneScape's Twitter account. 8 June 2018. Archived from the original on 30 May 2020. Old School RuneScape: "We've just hotfixed the falling body parts during the Pestilent Bloat encounter so they will now fall a little slower."

[4] Jagex. Mod Ash's Twitter account. 17 September 2019. Archived from the original on 30 May 2020. Mod Ash: "The Bloat and certain cutscene NPCs have a hack to pretend they're running, but that only works for pre-defined paths"

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