TL;DR
Guillotina is the first House Boss in Mewgenics, summoned after you clear the Boneyard. You get a 7-day timer to prep before she shows up at your House. She is a two-phase fight with 400 HP on Normal (480 Hard, 560 Crazy, 640 Impossible), and you win on positioning and damage-over-time, not burst. Stack Bleed, Burn, and Poison, give every cat a mobility skill so you can hit and retreat, and keep one open tile behind each cat to survive her grabs and knockback. At half HP she transforms, heals, and wipes every debuff you stacked, so re-apply your DoT the instant she changes. In phase 2, never park a cat inside her reach: she can Swallow it and Digest it for an instant kill plus 25 HP back to herself.
Who Guillotina Is and When You Fight Her
Guillotina is the game's first House Boss. She does not appear on a normal map. She comes to you, fought at the House once you complete the Boneyard for the first time. After that clear, you have 7 days to ready your roster before the fight triggers. Kill her and you walk away with the item:throbbing-gristle, the quest item that opens the Throbbing Domain.
Use the 7 days. This is the first fight that punishes a thrown-together team, and the prep window exists so you can breed and train cats with the right skills rather than scrambling on the day.
Her Stats
On Normal she sits at 400 HP. The scaling climbs with difficulty: 480 on Hard, 560 on Crazy, 640 on Impossible. Her base Damage is 5, Movement Range is 3 (it rises to 4 in phase 2), Luck is 5, and she occupies a 2x2 footprint, four tiles of board space that block your lanes and make her grabs hard to dodge. She also carries 3 stacks of Trample.
The number that does not show on the stat sheet matters most: she acts several times each round. Multiple actions per turn is the core of her difficulty. One cat caught flat-footed can eat two or three hits before you ever get to respond, which is why spacing beats raw stats here. If you want the full breakdown of how multi-action turns work, see the action economy guide.
Phase 1: Grabs, Throws, and Spacing
Phase 1 runs from full HP down to the halfway mark. Her kit is built around dragging your cats out of position and slamming them into walls.
Toss picks up an adjacent cat and throws it diagonally until it hits an obstacle, dealing damage on landing. Inhale reaches up to 10 tiles in a straight line and sucks a cat in; while inhaled, that cat can do nothing but Flail. Spit then expels the inhaled cat about 6 tiles away for 1 damage. Leap, which some players call the Butt Slam, jumps her a tile and deals damage with knockback to anything in the landing zone and along the path.
Flail is your only escape from an Inhale, and it often fails. Treat being inhaled as a lost turn for that cat and plan around it: keep your other three cats spread so a single grab does not leave the rest clustered for a follow-up Leap.
The throughline for phase 1 is spacing. Spread out to deny clean Trample and Leap lanes. Side-step after she commits to a move. Most importantly, leave one open tile behind every cat. That escape tile is what turns a Toss or a knockback from a kill into a recoverable shove.
The Phase 2 Transition (The Part That Loses Runs)
When Guillotina drops to 50% HP (200 on Normal), she roars and transforms into a faster, meaner form. The transition does four things at once: she heals roughly 50 HP, gains +100 to her max HP, raises Movement Range from 3 to 4, and, the detail that wrecks careful play, cleanses every debuff on herself.
That cleanse is the trap. All the Bleed, Burn, and Poison you stacked through phase 1 vanishes at the halfway mark. If you do not know it is coming, you watch a near-dead boss shrug off your entire DoT setup and come back swinging with a bigger health bar.
The counter is simple once you expect it: re-apply your damage-over-time the instant she transforms. Do not waste the early phase-2 turns repositioning if you can land fresh stacks first. The faster the new DoT ticks start, the less her +100 max HP actually costs you.
Phase 2: Swallow and Digest
Phase 2 trades the throw-loop for a kill-loop. Swipe hits an adjacent cat and applies 10 knockback. Leap returns for 3 damage with knockback. The dangerous chain is Swallow, Belly Pound, and Digest: Swallow inhales a cat from up to 10 tiles away and holds it in her stomach, Belly Pound deals 5 damage to that swallowed cat, and Digest instantly kills it while restoring 25 HP to Guillotina.
That is the run-ender. A single swallowed cat is a dead cat and a 25 HP heal handed to the boss. Never leave a cat parked inside her reach in phase 2. If one does get swallowed, your turn-one priority is to either burst her down or reposition the rest of the team, because Belly Pound plus Digest will finish that cat fast and there is no Flail option to lean on.
How to Counter Her
Damage over time is the headline. Bleed, Burn, and Poison deal damage independent of her HP pool, so they keep working no matter how she scales. Bleed and Burn whittle her down through phase 1; Poison is the pick for shrinking the phase-2 HP swing. Just remember the cleanse and reload your stacks after she transforms. The status effects guide covers how each DoT stacks and ticks.
Mobility is the most important defensive trait. Give every cat at least one movement skill. The whole fight is hit-and-retreat: strike, then step out of her range before she commits her next action. Strong knockback of 4 or more tiles also lets you kite her and reset spacing on your terms.
Slow her action economy. Immobilize and Petrify cut the number of actions she takes per turn, which directly defangs her multi-action rounds. Confusion is strong too: a confused Guillotina can turn her own attacks on herself.
Pick the right elements. Water skills grant dodge bonuses. Ice is more viable than Fire here, since Fire spreads through the arena and can backfire on your own cats. Tall grass gives a 50% dodge chance, which makes it ideal cover for a Thief setup that darts in and out.
A Team That Works
You bring four Retired cats into this fight, so build the composition around coverage. A clean four-cat answer: a Cleric for heals, a Hunter for ranged damage that never has to enter her grab range, a Tank to hold the frontline and absorb Swipes, and a Thief that backstabs from tall grass under the 50% dodge bonus. Every one of those four should carry a mobility skill and a way to apply or refresh DoT. The class tier list ranks each of these picks if you are still deciding who to breed.
Build that team, respect the spacing, and keep your DoT topped up across the transition. Guillotina is the wall that teaches positioning. Once she falls and the Throbbing Gristle drops, the lessons carry straight into every House Boss after her.