Judas

What you start with

The mechanics that actually govern this character.

• 1 red heart container, 3 coins, and a 1.35x damage multiplier, the highest of any non-tainted character in his base form.
• The Book of Belial: 3-room charge, +2 damage for the current room, and while held it adds +12.5% to the Devil or Angel door chance. The pre-Afterbirth guaranteed deal room no longer applies in Repentance.
• Extra Belial uses in the same room stack for +1 damage each in Repentance, and XV - The Devil stacks on top of it.
• Black Judas (via Judas' Shadow on death) spawns with 2 black hearts, a 2.00x damage multiplier and 1.1 speed. In Repentance he cannot gain red heart containers at all, but he counts as Judas for every achievement, unlock and completion mark.

How to play them

• One container means one mistake. On floors 1-2, health ups outrank damage ups; you already carry a 1.35x multiplier that nothing else can match.
• Use Belial before every boss and every dangerous room. +2 flat damage sitting behind a 1.35x multiplier is a larger relative swing on Judas than on anyone else.
• Take Dead Cat if you see it. Judas already sits at one container, so nine lives costs him essentially nothing.
• Low-health triggers are permanently on for him: Scapular, Whore of Babylon, Monkey Paw, Glyph of Balance and Dark Prince's Crown all fire from the moment you take a single hit.
• Soul and black hearts are the only health he can safely spend on Devil deals. Bank them from Ceremonial Robes, The Pact, Book of Revelations or Satanic Bible before shopping the Devil pool.
• Only take one-heart Devil deals unless you have soul hearts stacked. A two-heart deal at one container is a death sentence, not a trade.

Items to hunt for

Strong on this character specifically, not just strong.

• Birthright: Belial becomes a passive that sits underneath another active, like Book of Virtues, and grants +0.66 damage per charge of the item above it. A 12-charge active parked on top is roughly +8 permanent damage.
• Blood of the Martyr: makes Belial apply a 1.5x damage multiplier on top of its +2. Note it does not stack with the multipliers from Cricket's Head or Magic Mushroom.
• Car Battery: Belial goes from +2 to +3 damage per use.
• Whore of Babylon: with one container he sits at half a heart or less almost permanently, making it a near-constant +1.5 damage and +0.3 speed.
• Ceremonial Robes, The Pact and Abaddon: soul-heart-priced Devil items that hand back black hearts, so they give Judas health he can spend rather than health he has to protect.
• 9 Volt: Belial is a 3-room charge, and the partial charge on room entry makes it close to per-room.
• Schoolbag: lets him keep Belial while carrying a second active, and with Birthright the second active is exactly what Belial scales off.

Traps to refuse

Picks that are neutral or good elsewhere and bad here.

• Two-heart Devil deals and Black Market items before you have a soul heart buffer. One container is the whole budget.
• Blood Donation Machines and Devil Beggars: they take red hearts first, and he only has two half-hearts of them.
• Rerolling Belial away with a D4 or a Dice Room before you have a real damage source. The 1.35x multiplier alone does not carry Chapter 3.
• Bucket of Lard and other speed-down health ups: his base speed is 1.0 and his survival plan is not getting hit at all.

Cheese and techniques

Verified against 1.7.9 on console — anything patched, PC-only or Repentance+ only is called out rather than listed.

• Judas' Shadow is an upgrade disguised as an extra life. Dying respawns him as Black Judas at a 2.00x damage multiplier with 2 black hearts, and every mark and unlock still counts for Judas.
• Belial's +12.5% deal chance stacks with +99% for a hitless floor and +35% for a blown-up beggar, so Judas can sit at the displayed 100% deal chance on almost every eligible floor just by holding it.
• Room-long effects last the whole Beast fight. Fire Belial at the start of the Ultra Famine phase and the damage bonus persists through all four Ultra Harbingers and The Beast herself.
• Every Ultra Harbinger killed grants 2 active-item charges, so Belial can be re-used repeatedly across the Beast fight rather than once.

Getting the marks

• Black Judas earns every Judas mark, so a Judas' Shadow death mid-run never costs you the completion note.
• Mother and The Beast are his hardest marks, because from Chapter 4 onward every hit is one full heart and he starts with two half-hearts.
• Belial's deal-chance bonus fights the Mega Satan mark: Devil deals permanently close Angel Rooms, and both Key Pieces come only from angel statues. Hold Belial for the door chance but refuse the deals if Mega Satan is the target.