Berserk is the 1st stage of The Crazed Axe. Next stage: Unjust War.
Crazed Axe Cat comes out the moment the battle starts: 2,200,000 HP, 360 range, fast area hits that Freeze whatever is in front of him. He isn't what usually ends the run, though. From 1:13 the Shy Boys start arriving, Red and Floating, at 900% strength, very fast. They keep coming for the whole fight, and they break your wall so Crazed Axe can walk through it. Once he's through, he freezes your expensive units and kills them. So the stage is two jobs: keep a wall in front of Crazed Axe at all times, and stop the Shy Boys with crowd control from a stack of ranged units behind that wall.
The lineup that does it
Ten units, no gacha. The wall: Crazed Macho Cat, Eraser Cat, Macho Cat and Crazed Wall Cat. The stack: Macho Leg Cat, Crazed Whale Cat (it hits Red, so it chips the Shy Boys), Dragon Cat and Crazed Dragon Cat. Dragon Cat and Crazed Dragon Cat outrange Crazed Axe (400 against his 360) and do most of the work from behind the wall. Holy Valkyrie is there for her Freeze, not her damage, and Crazed Bahamut is the big hitter. Eraser Cat matters: Wall Cat at the same level can't hold nearly as well. Plain Dragon Cat is fine here, even preferable to King Dragon, because its shorter recharge builds the stack faster. If you haven't cleared the other Crazed stages, do them first. Crazed Whale and Crazed Dragon are hard to replace, and Crazed Axe Cat himself barely helps anywhere else.
Treasures and items
Every Empire of Cats treasure at Superior. From Into the Future, only Blood Fruit and Sky Fruit matter: every enemy here but Crazed Axe is Red, and the Shy Boys are Floating too, so these two make Holy Valkyrie's Freeze and Crazed Whale's anti-Red hits land harder. The rest of Into the Future is anti-Alien and does nothing here. Bring Rich Cat, because Crazed Axe is on you from second one and you need money for a stack before the Shy Boys arrive. Bring Cat CPU for the long middle of the fight. Sniper the Cat is on the wiki's list and helps against the Shy Boys, but know the trade-off: any knockback, the cat cannon included, can push enemies out of Crazed Bahamut's shot. Hold the cannon unless you have Slow Beam on it.
The first minute: stall, don't fight
Turn Cat CPU off for the start, or it spends your money the moment you have any. Hold Crazed Axe with Crazed Wall Cats alone, sending one each time the recharge comes off. At that rhythm one dies just as the next arrives, so you never pay for two at once. Put a second one down if he starts creeping forward. When Sir Seal walks in, send Dragon Cats to hit it from behind the wall. It pays well, and by the time the Shy Boys are due you should be in five figures.
Crazed Wall Cats holding Crazed Axe alone · plays here, from that second
When the Shy Boys come, build the stack
At five figures, put out the whole wall and start stacking: Dragons, Macho Leg, Crazed Whale. When the second Shy Boy appears, send Crazed Bahamut, then Holy Valkyrie. Keep about 8,000 banked for those two, and turn the CPU on only after Bahamut's first shot lands, so it has money for new meatshields rather than spending all of it at once. From there the rule is simple: the wall never goes empty. If Crazed Axe reaches your stack, he freezes it and the run is over.
the stack out, Holy Valkyrie in, the CPU taking over · plays here, from that second
Luck, and when to restart
Without gacha units, Holy Valkyrie's Freeze is the only thing reliably stopping the Shy Boys, and it's a chance per hit. Some runs it won't proc, the Shy Boys pile up, and the wall collapses before she recharges. When the enemies start reaching your base, pause and force-close, rather than playing it out. The stage lets you back in without spending energy or items, and a fresh start is better than a lost run. Crazed Bahamut misses often too; if you don't see Shy Boys getting knocked back after his shot, he missed. Once a run holds its first two or three Shy Boys, the stack snowballs: one replaces each that dies, but only one or two are ever on the field, and the CPU finishes it.
a run where the Freeze didn't come, paused to force-close · plays here, from that second
How a winning run looks
A thick wall of Walls and Macho Cats, Dragons stacked behind it, Bahamut and Valkyrie re-sent by the CPU as they fall, and Crazed Axe standing still being chipped down. Nothing clever happens after that. It's the wall holding while the stack does the damage.
the stack at full size, the CPU running it · plays here, from that second
With gacha units
Anything with anti-Red or anti-Floating crowd control makes this far easier: every extra chance to stop a Shy Boy is one fewer that reaches the wall. Ururun Cat is the best swap for Holy Valkyrie. Use it the same way, knocking the enemies back instead of freezing them, and it outranges Crazed Axe. Bath Cat (Sexy Bathtub Cat) outranges him too and deals massive damage to Red. Paris or Cyborg Cat (Salon Cat's forms) and Drama Cats work as extra ranged hitters, and Cutter Cat is a rusher that shreds the Shy Boys. Any Uber with more than 360 range that hits Red or Traitless belongs here. Check its range on the wiki before you trust it.
THE SHORT VERSIONStall Crazed Axe with Crazed Wall Cats on cooldown, build a Dragon stack behind a wall that never empties, send Bahamut and Holy Valkyrie on the second Shy Boy and let the CPU run it, and force-close any run where the Freeze doesn't come. Full EoC treasures, Blood and Sky Fruit, Rich Cat and Cat CPU. Do this Crazed stage last.
The general approach, from the wiki's strategy notes. The guide above walks through one full clear.
The Shy Boy rush early on is what brings your defenses down; Crazed Axe's fast, hard, average-ranged attacks do the rest, which makes nukers a liability.
- Rich Cat, Sniper the Cat and Cat CPU are all recommended, with more than two meatshields (Crazed Cat, Eraser, Crazed Wall).
- Slow, freeze or Red/Floating damage helps — Bodhisattva Cat and similar Ubers; Island Cat and Crazed Fish Cat are useful too.
- Stack ranged units and skip nukers; the wiki suggests doing this Crazed stage last, since Crazed Axe Cat is a weak reward but the clear unlocks the Manic stages.
CRAZED MACHO CAT A Wall in the guide's clear. 
ERASER CAT S Wall in the guide's clear. 
MACHO CAT D Wall in the guide's clear. 
CRAZED WALL CAT S Wall in the guide's clear. 
MACHO LEG CAT A Ranged in the guide's clear. 
CRAZED WHALE CAT A Anti-Red in the guide's clear. 
DRAGON CAT B Outranges in the guide's clear. 
CRAZED DRAGON CAT A Outranges in the guide's clear. 
HOLY VALKYRIE CAT A Freeze in the guide's clear. 
CRAZED BAHAMUT CAT A Big hitter in the guide's clear. 
⚙ Trait counters worked out from the roster — the guide's plan doesn't need them; kept for reference
Crazed Axe Cat is Traitless. Anti-Traitless units take less damage and deal more.
HITMAN CAT A Hitman Cat: Deals massive damage to Traitless enemies 
BOWLER CAT A The Slow lands on Traitless enemies — great for stalling the many Traitless bosses across Empire of Cats and Into the Future. 
DRILLER CAT A 100% Weakens Traitless to 10% and (True) Strong vs Traitless. Also fits “Out-range Crazed Axe Cat.” 
D'ARKTANYAN S Strong Against Traitless on a Long-Distance area attack — answers the many Traitless bosses. 
JAGANDO JR. A Lord of Ruin Jagando Jr.: Strong against Traitless enemies (Deals 1.5x damage, only takes 1/2 damage) Crazed Axe Cat reaches 360 range. Units that out-range it can chip safely without taking hits.
LIZARD CAT B Range 400 — fires from beyond its 360. 
MASTER URIL A Range 405 — fires from beyond its 360. 
AKU RESEARCHER A Range 400 — fires from beyond its 360. DRILLER CAT A Range 460 — fires from beyond its 360. Also fits “Counter Traitless.” 
CHILD OF DESTINY PHONO S Range 600 — fires from beyond its 360. Also fits “Burst the boss down.” Crazed Axe Cat has a deep HP pool (2,200,000+ even before stage magnification). Heavy single-target burst shortens the fight.
BAHAMUT CAT S Huge multi-hit burst — a story-unlock powerhouse that deletes tanky enemies. 
MIGHTY REKON KORPS S Among the highest single-hit Area damage available. Also fits “Out-range Crazed Axe Cat.” 
GAIA THE CREATOR S Long-Distance multi-hit with Insane Damage — a generalist wall-cracker. Also fits “Out-range Crazed Axe Cat.” 
CRAZED MONEKO A Big crit burst against tanky/Metal targets. 
TECOLUGA S A 7,300-AP long-range hit obliterates tanky targets when the Critical connects. Also fits “Out-range Crazed Axe Cat.” 
The castle you destroy to clear the stage.