Bosses

ASKBossBase · ASKBossPart

A boss is an enemy with phases. Each phase is a health threshold that swaps the boss's weapon set and movement speed, and can introduce new destructible parts. Everything is data on the Blueprint — there is no state machine to write.

Bosses also drive the boss health bar and pause the world scroll for the duration of the fight.

Phases

Add entries to Phases, ordered from full health downward. As the boss's health falls past each threshold it enters that phase, replacing its weapons wholesale.

Property	Default	Purpose
Health Threshold Percent	100	The health percentage at or below which this phase begins. The first entry is normally 100.
Move Speed	0	Movement speed during this phase. 0 keeps the current speed, so a phase can change only its guns.
Weapons	—	The complete weapon set for this phase. Mounts are rebuilt on entry, so the previous phase's guns are gone.

Phase weapons

Each entry creates one gun on the boss for the duration of the phase.

Property	Default	Purpose
Weapon Data	—	The weapon to fire — the same assets the player uses.
Level	0	Which power tier of that weapon to fire at.
Mount Offset	0,0,0	Where this gun sits on the boss.
Fire Direction	-1,0,0	Which way it shoots. Defaults to down-screen, toward the player.
Fire Interval	0	Staggers this gun against the others, so a bank of cannons ripples instead of firing as one. 0 fires immediately.

Entrance and invulnerability

Property	Default	Purpose
Attack On Spawn	On	Begin attacking immediately. Turn it off for a scripted entrance, then call Begin Attacks when the boss is in place.
Invulnerable Until Attacking	On	The boss cannot be hurt until attacks begin, so it can't be shredded during its fly-in.
Phase Transition Invulnerability	1	Seconds of immunity when changing phase, so a burst of damage can't skip a phase entirely.

A typical scripted entrance: turn off Attack On Spawn, fly the boss into position with a path or an animation, then call Begin Attacks. Immunity lifts at the same moment, so the fight starts fairly.

Destructible parts

ASKBossPart

Parts are separately damageable pieces attached to the boss — turrets, wings, armour panels. Each has its own health and dies independently, which turns one health bar into a fight with structure.

Property	Purpose
Part Class	The SKBossPart Blueprint to spawn.
Mount Offset	Where it attaches on the boss.
Introduced At Phase	Which phase it appears in, so a later phase can unfold new weak points. 0 means present from the start.

A part has its own health component and its own weapon mount, so it can shoot back. Its Lag Speed controls how loosely it trails the boss's movement — a small amount of lag makes a large boss feel heavy rather than rigid.

Blueprint hooks

Event	Fires
On Boss Phase Changed	On entering a phase, with the new index. Use it for a roar, a screen shake or a colour change.
On Boss Part Destroyed	When a destructible part dies, with the part.
On Boss Defeated	When the boss dies, before the stage-clear sequence.
Get Current Phase	Returns the active phase index.

The world stops for a boss

The scrolling background pauses while a boss is active, so the fight happens on a held frame rather than sliding past. This is controlled on the scrolling component:

Property	Default	Purpose
Pause During Boss	On	Hold the world still for the fight.
Resume After Boss	Off	Off means the world stays stopped after the kill, giving the stage-clear sequence a still frame. Turn it on for a mid-level boss the stage continues past.

Pickups keep drifting during the pause, since they carry their own scroll speed. A placement spawner rides the terrain, so its points freeze too and no enemies wander in mid-fight.

Building a boss

Where next