Boss Rush

Boss Rush Mode is an alternative game mode that is accessible in the starting area of the Prisoners' Quarters. In this mode the player can fight bosses back-to-back with items they receive throughout the trials, without travelling through the regular biomes. It has 4 stages, with only the first being unlocked at the start. Completing a stage will unlock the next one.

To access the Boss Rush, one needs to encounter at least 5 bosses (two Tier 1, two Tier 2 and one Tier 3). If the player has encountered additional bosses, then those can be randomly chosen as a Tier 1/2/3 boss during a trial.

At the start of a rush, there is a choice between Brutality, Tactics and Survival in the form of three Stat-Stones. Choosing one will automatically give the player stats relevant for the chosen colour and supply the player with 3 choices of relevant builds at the start of the stage in the form of tubes. Once a colour is chosen, the play won't be able to change the colour, nor find items that don't scale with the main stat during the run. Interacting with a second and third Stat-Stone will increase the stats of the player.

In every transition room:
 * Guillain: Players are able to choose mutations in every transition room during a stage.
 * Rerolling mutations in any stage after the first will cost gold.

After every boss in the 1st & 2nd Stage and after every two bosses in the 3rd & 4th stage:
 * Stat-Stone: Interacting with it gives the player more stats.
 * Item-Altar: A two-choice-altar (with a weapon and a skill) will appear at the beginning of the transition area.
 * If the previous boss has been slain flawlessly, then a legendary three-choice-altar (with one guaranteed weapon & skill) will appear instead.
 * A colourless three-choice-altar will appear at the beginning of a run, which can contain items that wouldn't normally scale with the chosen colour.
 * Blacksmith: Players are able to upgrade items or reroll their affixes.
 * Upgrading an item costs 800 gold.
 * Rerolling affixes costs 200 gold.
 * Shops: Two shops (weapon & skill) will provide the player with more gear.
 * Items cost 1750 gold.
 * Currently the player can acquire off-colour gear by buying items from the shops.

At the end of a run:
 * Legendary Forge: After the run has been completed, the player gets the choice to invest their Cells into the Legendary Forge.
 * Loot: A chest that contains rewards is located at the end of the last transition area, alongside the Mentor Knight NPC.

Items
Rewards are locked behind each stage.
 * (stage 1 victory on 0 BSC)
 * (stage 2 victory on 0 BSC)
 * (stage 3 victory on 0 BSC)


 * 8 Skins, 4 barbarian skins and 4 victorious beheaded skins.

The statue
A statue of the Beheaded, which has customizable parts. The statue itself is unlocked by beating the first stage at 0 BSC. New parts are locked behind Boss Rush victories. To unlock every statue reward, the player needs to clear every stage at least 6 times:
 * 0-2 BSC
 * 3-4 BSC
 * 5 BSC
 * Same difficulties but flawlessly

Stages
There are 4 different stages in Boss Rush, with each being harder than the previous. A 3 bosses and 5 bosses stage, without and with modifiers. The player will be fighting alternative versions of bosses with extra abilities in the stages with modifiers.
 * Stages 1:
 * 3 bosses back-to-back
 * One Tier 1, Tier 2 & Tier 3 boss
 * Stage 2:
 * 3 bosses back-to-back with modifiers
 * One Tier 1, Tier 2 & Tier 3 boss
 * Stage 3:
 * 5 bosses back-to-back
 * Two Tier 1, two Tier 2 & one Tier 3 boss
 * Stage 4:
 * 5 bosses back-to-back with modifiers
 * Two Tier 1, two Tier 2 & one Tier 3 boss

Bosses will be selected from these 3 tiers:
 * Tier 1:
 * The Concierge
 * Conjunctivius
 * Mama Tick
 * Tier 2:
 * Time Keeper
 * The Giant
 * The Scarecrow
 * Tier 3:
 * The Hand of the King
 * The Servants (final fight)
 * The Queen

The Concierge

 * Twins: A second Concierge is in the fight.
 * They don't scream or create a force shield upon changing phases.
 * They only have 3 phases
 * They don't use the Leap attack (stage 4 attack).
 * They don't gain attack speed on low HP (stage 5 & 6 mechanics).

Conjunctivius

 * Conjunctivius only moves once instead of twice between attacks.
 * Spawns up to 4 Tentacles continuously. (Needs verification)
 * She only has one Tentacle Phase:
 * Activates when she reaches 50% HP.
 * Will spawn 5 additional Tentacles.
 * If one didn't slay the continuously spawning Tentacles, then there can be up to 10(?) Tentacles.
 * She screams a total of 5 times:
 * 1st scream at 90% HP (Bullet Hell afterwards)
 * 2nd scream at 70% HP
 * 3rd scream at 50% HP (Tentacles afterwards)
 * 4th scream at 30% HP (Bullet Hell afterwards)
 * 5th scream at 10% HP

Mama Tick

 * New attack: Unique Scythe Stabs that move from:
 * Left to right
 * Right to left
 * Middle to edges
 * Edges to the middle

Time Keeper

 * Heals to full health after transitioning to her 3rd phase.
 * She skips her first phase on 1BC+.
 * General cooldown reduction on attacks and between attacks.

The Giant

 * Has 4 hands instead of 2
 * Attacks with two hands in quick succession (double swipe, double slam, slam-swipe, etc.).
 * Starts in phase 3.
 * Doesn't scream to change phases because of this.

The Scarecrow

 * Stomp:
 * Throws 4 Sickles instead of 2 per Stomp.
 * Seed Throw:
 * Throws 2 Sickles per Seed Throw.
 * Can now spawn up to 4 mushrooms instead of only 3.
 * Pitchfork Jab:
 * Can spawn a Yeeter with the first attack.

The Hand of the King

 * Has a different AI that forces more moves (Slash-Slam into Super Slam, 4 Charges, etc.).
 * Has a new two-combo attack:
 * The first Slash's hitbox extends behind HotK and has the sound cue of the Time Keeper's Hook Throw.
 * The second Slash is similar to the third Slash in his Triple-Slash attack.
 * Added a 2nd slam after Slash-Slam.
 * Doesn't use his Exploding Flags attack anymore.
 * Starts in Phase 3, but has an enemy phase.
 * Spawns HPC enemies during phase change.

The Servants

 * Arena now has wall Spike & Ball Spike traps on the walls and ceiling.
 * They are more aggressive.
 * All three servants can be in the arena at the same time.
 * Euterpe is stronger:
 * She can use her normal attack up to 5 instead of 3 times.
 * Her Arrow Salve will fire 15 (3x5) instead of 9 (3x3) arrows.
 * Her Stomp will be damaging even after she had landed.

The Queen

 * Normal attacks cause Reality Slashes with different angles:
 * Slash: Upwards angle
 * Stab: Horizontal
 * Lower-Stab: Downwards angle
 * Special attacks cause Reality Slashes with different angles:
 * Down-Strike: Vertical
 * Dashing-Strike: Horizontal
 * Her Melee Parry causes another horizontal Reality Slash (needs confirmation)
 * Is invulnerable during her Reality Slashes.
 * Her 2nd Reality Slashes phase is faster.

Gear & Stats
A build can be selected at the start of a stage by choosing one of the three Stat-Stones. In the next room, three tubes with starting gear are provided. Each boss drops loot in the form of two items (one weapon and one skill) and some gold. The last boss will only drop cells, which can be invested into the Legendary Forge.

The player will only encounter items of the chosen colour (done by interacting with a Stat-Stone at the start of a trial), only the unlocked items will appear, and Custom Mode settings won't apply.

Three items are disabled during Boss Rush:
 * Giant Killer
 * Spoiler Skill
 * Wish Mutation