Forbidden Box is one of the most-searched items in Vampire Survivors, but here is the critical clarification: it is not a relic. "Forbidden Box" is the spell code forbiddenbox that you cast in the Forbidden Scrolls of Morbane to unlock Room 1665, a hidden 30-minute stage added in Patch 1.11 (August 2024). Inside that stage, after killing 1,665 enemies to open all 16 rooms, you pick up the Darkasso relic, which permanently unlocks the Darkana card system.
This guide explains why the search term "Forbidden Box" is misleading, how to set up the spell chain properly, exactly how Room 1665's 16-room kill-milestone progression works, the final-room Darkasso pickup, and what the Darkasso unlocks once you have it.
Most Vampire Survivors relics follow a predictable naming pattern: you search the name, find a wiki page, and read the effects. Forbidden Box breaks that pattern because it is not the name of a collectible item. It is the spell code Poncle chose as the key phrase for unlocking Room 1665.
The confusion comes from two sources. First, the word "forbidden" shows up on several nearby items: the Forbidden Scrolls of Morbane (a real relic that unlocks the Secrets menu), the Holy Forbidden stage (the hidden area where the Yellow Sign lives), and now forbiddenbox as a spell code. Second, the Room 1665 achievement is literally titled "Dare to cast the spell 'forbiddenbox'", which reinforces the phrase even though no object named "Forbidden Box" exists in the game.
Here is what the term actually refers to, in order of how a player typically encounters them:
forbiddenbox: Typed in the Secrets menu, it immediately unlocks Room 1665 on your stage list.Unlike most spells in the Forbidden Scrolls of Morbane, which are alternate shortcuts to normally-unlockable content, forbiddenbox is the only way to unlock Room 1665. There is no in-game progression path that reveals this stage without the spell. The achievement text itself instructs the player to cast it, confirming it is the canonical route.
You cannot cast the forbiddenbox spell until you have the Forbidden Scrolls of Morbane, the relic that unlocks the Secrets menu where spells are cast. Most players already have this by the time they hear about Room 1665, but if you do not, here is the fast version:
There is one alternate way to access the Secrets menu without collecting the Forbidden Scrolls of Morbane: tap the Yellow Sign icon in the Collection menu seven times. This works as a shortcut but still requires the Yellow Sign relic to be unlocked first. Most players will find the Sketamari route simpler.
With the Forbidden Scrolls of Morbane in hand, casting the spell is straightforward:
forbiddenbox in the text input. All lowercase, no spaces, no quotes.Simply casting the spell unlocks the achievement \"EXTRA: Room 1665\" (5 Gamerscore / Bronze PSN trophy). You get this before you even play the stage, just for typing the spell correctly.
Room 1665 is one of the most mechanically unique stages in Vampire Survivors. It does not play like a normal 30-minute run. When you enter, you are locked in a small room at the top of a 16-room vertical structure, and your job is to kill enough enemies to unlock each subsequent room below you.
On entry to Room 1665, the following happens:
Each new room opens at a specific cumulative kill count. There are 16 rooms total (your starting room plus 15 unlockable rooms). The milestones are:
| Room | Kills Required | What It Contains |
|---|---|---|
| 1 (Spawn) | 0 | Empty starting room |
| 2 | 100 | First Arcana chest |
| 3 | 200 | Standard room |
| 4 | 300 | Standard room |
| 5 | 400 | Standard room |
| 6 | 500 | Standard room |
| 7 | 600 | Second Arcana chest area |
| 8 | 700 | Standard room |
| 9 | 800 | Standard room |
| 10 | 900 | Standard room |
| 11 | 1,000 | Standard room |
| 12 | 1,100 | Standard room |
| 13 | 1,200 | Standard room |
| 14 | 1,300 | Standard room |
| 15 | 1,400 | Standard room |
| 16 (Final) | 1,665 | The Darkasso relic |
The final jump is the important one: the last room does not open at 1,500 kills as the pattern would suggest. It opens at 1,665 kills, which is where the stage gets its name. That final stretch from 1,400 to 1,665 is 265 extra kills on a build that has already carried you through the previous 14 rooms.
A few behaviors in Room 1665 are different from every other stage in the game. These are the details that separate a successful run from an early death:
In normal stages, enemies offscreen eventually despawn to free up processing. Not here. Every enemy you do not kill stays alive and keeps tracking you across the 16-room layout. If you back into a previously-cleared room, the enemies you ran past earlier are still waiting. Build for sustained AoE damage, not hit-and-run.
Each corridor between rooms contains 11 to 12 light sources at predictable positions. Unlike normal stages where light sources are single-use, these slowly respawn over the course of the run. This gives you a steady supply of Floor Chicken heals, coins, and Orologion stops if you revisit cleared corridors.
The stage gets progressively darker each time a new room unlocks. By room 10 or so, visibility is noticeably reduced. Then when you unlock the final room at 1,665 kills, the entire stage suddenly lights up again as a visual reward for reaching the Darkasso.
The wiki documents several split-second visual details that appear during gameplay: blood drips down from the top of the screen after enough kills, a large eye occasionally appears on the walls, shadows of arms reach up from the bottom of the screen, and a mouth with sharp teeth plus a pair of eyes appears in the empty space outside the playable rooms. These are cosmetic only and do not signal any mechanical change, but they reinforce the stage's horror atmosphere.
One counterintuitive detail: boss enemies in Room 1665 typically have lower HP than the regular trash enemies that spawn around them. The stage is tuned this way because the horde itself is the main challenge, not individual bosses. Focus your damage on clearing waves rather than dueling boss-tagged spawns.
The type and mix of enemies you encounter shifts based on (a) how many rooms you have unlocked and (b) how much time has passed. The stage has a 30-minute time limit, but most players reach the Darkasso well before 30 minutes with a decent build, because the unlock threshold is kill-based, not time-based.
Once you hit 1,665 kills, the final room opens at the bottom of the 16-room chain. Walk south through the corridors into the center of that last room. The Darkasso is floating there. Walking near it triggers an automatic pickup animation; you do not need to interact with it manually.
The Darkasso pickup does two things immediately:
The Darkasso menu has the same grid layout as the Randomazzo (standard Arcana menu), but the background is a writhing wall of red tentacles and the cards themselves have dark backing. Obtained Darkanas appear with a yellow highlight circle and sort to the top of the grid. Unobtained Darkanas show as face-down card backs.
Once you have the Darkasso, the run has nothing else to offer. The wiki explicitly notes this: there is no additional loot, no hidden secondary objective, nothing past the final room. You can continue grinding for XP and gold, but the stage considers itself functionally complete once you collect the relic. Most players quit the run immediately after the pickup animation.
If you only care about unlocking the Darkana system and not playing through Room 1665, there is a second spell that skips the whole stage:
darkassami — cast in the Forbidden Scrolls of Morbane. This awards the Darkasso relic directly without requiring you to play Room 1665 at all.
The practical decision: use forbiddenbox first so you can play Room 1665 and earn the three achievements tied to it, then use darkassami only if you are on a save where you want the relic without the stage unlock for some reason. The achievements are:
Skipping Room 1665 via darkassami still gives you the Darkasso relic but forfeits the two stage-based achievements.
Darkanas are mechanically identical to Arcanas. They slot into the same three-Arcana-per-run cap (or five if you are playing Queen Sigma). What makes them unique is their theme: where Arcanas are named after tarot-like concepts (Twilight Requiem, Disco of Gold, Wicked Season), Darkanas take a darker, more aggressive approach.
Poncle's patch notes for Darkanas state plainly: "The only difference between Arcanas and Darkanas is their theme, functionally they are exactly the same." So do not expect Darkanas to be stronger or weaker than regular Arcanas. They are a parallel set, unlocked by different characters and conditions, that expands your total pool of pick-one-of-four options during an Arcana chest pull.
One mechanical bonus: if you have unlocked 23 or more Arcanas + Darkanas combined, Arcana chests now offer six random picks instead of four, plus one free Reroll per chest. This is a major upgrade for late-game flexibility.
The Moonlight Bolero (VI) Darkana you receive on Darkasso pickup has one additional perk worth knowing: special bosses it spawns can drop Arcana chests that contain a previously-unseen Arcana, giving you an alternate route to obtain Arcanas you have not yet unlocked through character progression. This chance remains active until all unlocked Arcanas have been collected.
No. Forbidden Box is not a relic. It is the spell code forbiddenbox that you cast in the Forbidden Scrolls of Morbane to unlock Room 1665, a hidden stage. The relic inside that stage is called the Darkasso, not the Forbidden Box.
Casting forbiddenbox in the Secrets menu immediately unlocks Room 1665 in your stage list. It also unlocks the achievement "EXTRA: Room 1665". The spell is the only way to unlock Room 1665 and is confirmed as the intended path by the achievement description itself.
You need the Forbidden Scrolls of Morbane (dropped by Sketamari in The Bone Zone). Open the Secrets menu on the main screen, type forbiddenbox, and confirm. Room 1665 appears immediately in your stage list.
1,665 kills to open the final room and reach the Darkasso relic. The 16 rooms unlock progressively: 100 kills for room 2, 200 for room 3, up to 1,400 for room 15, then a jump to 1,665 for the final room.
The Darkasso is the relic in the final room of Room 1665. Picking it up permanently unlocks the Darkana system (an additional set of Arcana-like cards) and awards the Moonlight Bolero (VI) Darkana directly.
Yes. Cast the spell darkassami in the Forbidden Scrolls of Morbane to get the Darkasso relic directly, without playing the stage. Note: this skips the two Room-1665-related achievements, so use it only if you do not care about those.
The name refers to the final kill milestone. The stage has 16 rooms, and while the first 15 follow a clean 100-per-room pattern (100, 200, ... 1,400), the last room requires reaching 1,665 total kills. The number is both the room count (16) and the kill count (1,665).
Only Arcanas and Limit Break. Hyper Mode, Hurry Mode, Inverse Mode, and Endless Mode all auto-disable when you enter the stage. This keeps the kill-milestone progression consistent for everyone.
If you like deep dives on one roguelike, you will probably like the rest of the library. Here are the hub pages and the most popular genre roundups on Rogue Ranker.
Wiki citations: Room 1665, Darkasso, Forbidden Scrolls of Morbane, Arcanas and Darkanas.
Sprites and screenshots sourced from the Vampire Survivors Wiki (vampire.survivors.wiki) under CC BY-NC-SA 3.0.