At the end of every organ, a giant immune cell guards the way on. Bosses pick their attacks at random, never repeat the same one twice in a row, aim where you're heading, and get more dangerous as their health drops.
Every boss uses the same three-stage structure: an enraged half, two shield phases with reinforcements, and a final frenzy.
The boss starts on the far side of the room from where you came in, and the room stays sealed until it falls
Attacks come on an uneven rhythm, never the same one twice in a row, aimed where you're going
Below 50% health it enrages: about 30% faster attacks and bigger volleys
At 2/3 and 1/3 health it raises a shield worth 18% of its max health and calls in reinforcements. Break the shield first
After the second shield it enters FINAL PHASE: attacks come 30% faster and every attack also throws a slow ring of 12 shots
Big attacks are telegraphed with flashing circles, lanes and on-screen calls like SNEEZE!, ENGULF! and SHOCKWAVE!
Every boss drops a named set piece of gear (the organ's best tier 40% of the time, one tier lower 45%, two tiers lower 15%; in Pandemic Game Mode an ordinary piece of that tier) plus Chaperone Proteins and 1–2 Ribozyme Cores (in Endless Game Mode; anywhere else they condense into Chaperone Proteins). Chaperones from kills come at half: about 2 from the boss itself and 1–2 per condensed core, and a chance of RNA and a Dormant Virion (never from the Brain's boss)
Retrovirus deals 50% extra damage to bosses
Beating a boss opens a passage to the next organ and leaves a DNA upgrade orb. The last boss ends the run in victory, and so does every boss in Pandemic Game Mode, where each infection is a single organ
From the Codex
The giant immune cell guarding the way to the next organ.
Fun fact: From the third organ on, every boss also has a signature skill on its own random clock, aimed at you.
A spinning orange cell packed with histamine. It circle-strafes the middle of the room and floods it with bursts. The counter is to stay close, because it never sneezes up close.
Histamine Burst: a ring of 14 shots, or 20 followed by a second offset ring when enraged
Sneeze: it swells and releases a room-wide shockwave ring you have to dash through. It never sneezes when you're close, and the farther you hang back the more often it does (up to about every other attack)
Histamine Charge: a marked lane and a 0.75 s wind-up (0.55 s enraged), then it rushes at you, as far as you were when it wound up plus a little past you (at least 160 points). Dodge it and it is EXPOSED for 1.6 s, taking double damage
Aimed fan of 5 shots. Once enraged, this becomes a call for 3 Neutrophils
A huge, slow, breathing phagocyte. It never stops lashing pseudopods at you and alternates between engulfing you and releasing surfactant bubbles.
Pseudopod Lash: on its own clock every 1–3 s, a telegraphed tendril straight at you. When enraged it lashes three at a time in a spread
Phagocytosis (Engulf): "INHALING…" with a ring sweeping inward for 0.7 s, then it drags you in for 2.2 s. Dashing breaks free, and its open core takes double damage
Surfactant Bubbles: 4 bubbles (6 enraged) drift after you and pop into rings of 8 shots. Once enraged it also calls 3 Neutrophils
It moves 50% faster once enraged
Each shield phase calls in 5 Neutrophils
Its chamber hits 20% harder than the rest of the Lungs
The antibody factory. It drifts and strafes behind a turning Immunoglobulin wall, so you have to circle around it while dodging antibody fans and platelet swarms.
Immunoglobulin Wall (IG WALL): every 4–7 s it raises a glowing arc on one side that slowly turns to follow you for 4.5 s. Hits from the front deal only 15% damage
Antibody Snipe (signature): a fast shot that forks into a Y just before it reaches you. It fires two when enraged
Antibody Fan: 12 slowing antibodies (17 enraged)
Opsonize: a flashing lock-on line, then a fast 8-shot volley. Each hit marks you to take 35% more damage for 5 s
Rapid Stream: 9 shots (12 enraged) at where you're going
Platelet Swarm: 7 Platelets (10 enraged), plus a 16-shot spiral ring once enraged
Commander of the germinal centre: a bristling blue lymphocyte that whips the whole room into a cytokine storm and keeps calling in B cells and helper T cells.
Germinal Center (signature): marks a circle where you're heading, then 9 antibodies (12 enraged) slam in on it from all sides, fast
Cytokine Storm: every other cell in the room gets faster and hits harder for 6 s, and non-boss cells gain a shield worth 20% of their health
Radial burst of 16 shots (22 enraged)
Summon: 4 B Cells, Plasmablasts or Helper T Cells (5 enraged)
Keeper of the intestinal crypts, full of gold defensin granules. Expect spiralling defensin streams, mucus barrages and granules lobbed right onto you.
Defensin Granule (signature): lobbed onto where you're going. It hurts if you're under it when it lands, then bursts into a ring of 10 defensins. It throws two when enraged
Spiral: 4 turning arms of shots (6 waves, 8 enraged)
Mucus Barrage: 5 warning circles (7 enraged) that land as hurtful, slowing puddles
Radial burst of 20 (26 enraged)
Bubbles: 4 (6 enraged) that drift after you and pop into rings of 8 shots
The liver's resident filter, a lumpy macrophage that nets you in crossing lashes, engulfs you and charges. It attacks on a quicker rhythm than the other bosses.
Sinusoid Net (signature): 2 lashes (3 enraged) that cross exactly where you stand
Pseudopod Lashes: a telegraphed spread of 3, or 4 in every direction when enraged
Engulf: pulls you in for 2.2 s while its exposed core takes double damage
Scar Pools: 6 (8 enraged) lobs land on warning circles around you and leave slowing patches
Charge: it swells and flashes for 0.55 s, then lunges. A dodged lunge leaves it EXPOSED for 1.2 s, taking double damage
The mother of every blood cell. It keeps making new ones (neutrophils, myeloblasts, platelets, even megakaryocytes and NK cells) between bursts, spirals and bone spikes.
Spicule Eruption (signature): bone spikes burst out of the floor one after another in a marked line from it all the way to you, one every 70 points (2 more past you when enraged), racing out fast
Summon: 5 Neutrophils, Monocytes or Myeloblasts (6 enraged)
Summon: a swarm of 8 Platelets (9 enraged)
Summon: 2 Megakaryocytes or NK Cells (3 enraged)
Radial burst of 22 (28 enraged)
Spiral: 5 turning arms of shots
Shockwave ring to dash through
Rapid stream of 10 (13 enraged)
When 12 summoned cells are already alive, it fires a burst instead of summoning more
The brain's last line of defence: a branching violet cell that lashes in every direction, summons glia and strikes down marked lines with lightning. Every hit you land is weakened by the blood-brain barrier.
Synaptic Prune (signature): a line flashes from it to where you're going, then lightning strikes down it 0.6 s later. It uses two angled lines when enraged
Lashes in every direction: 4 tendrils (5 enraged) spread around it
Spiral: 6 turning arms of shots
Summon: 3 Astrocytes or Resident Memory T Cells (4 enraged)
Engulf: drags you in while its exposed core takes double damage
Radial burst of 24 (30 enraged)
Charge: a lunge that leaves it exposed if you dodge
