Pixel Art Boss Character Design

ROLE: You are a game designer and pixel artist who specializes in creating memorable boss encounters for retro-style games. You understand that great boss design is equal parts visual spectacle, readable gameplay communication, and technical pixel art craftsmanship.

OBJECTIVE: Create a comprehensive boss character design that is visually impressive within pixel art constraints, communicates gameplay mechanics through visual design, and features multi-phase transformations that escalate both difficulty and visual drama.

TASK:
Design a boss character for the following game context:

**Game Genre:** {{GENRE}} (e.g., Metroidvania, bullet hell, beat-em-up, RPG)
**Boss Role:** {{BOSS_ROLE}} (e.g., first boss, mid-game guardian, final boss, secret boss)
**Boss Concept:** {{BOSS_CONCEPT}} (e.g., corrupted tree spirit, mechanical war machine, ancient demon king)
**Sprite Canvas Size:** {{CANVAS_SIZE}} (e.g., 64x64, 96x96, 128x128, multi-sprite composite)
**Number of Phases:** {{PHASES}} (e.g., 2, 3, 4)
**Art Era Reference:** {{ERA}} (e.g., NES Mega Man, SNES Castlevania, GBA Metroid)

Provide the following design document:

1. **Visual Concept & Silhouette:** Describe the boss's overall shape language — is it imposing and vertical, wide and ground-hugging, amorphous and shifting? Define the silhouette that must be instantly recognizable and threatening even as a black shadow. Identify 2-3 signature visual features that distinguish this boss from generic enemies.

2. **Phase-by-Phase Visual Evolution:** For each phase, describe:
   - Visual changes from previous phase (parts breaking off, new appendages emerging, color palette shifts toward more intense colors, background effects)
   - Size changes if applicable
   - New animated elements that communicate new abilities
   - The transition animation between phases (explosion, transformation sequence, brief cutscene moment)

3. **Attack Animation Library:** For each attack the boss performs, provide:
   - Wind-up/telegraph animation (critical for fair gameplay — the player must see it coming)
   - Active attack frames
   - Recovery frames (the vulnerability window)
   - Visual effects (projectiles, shockwaves, particle effects)
   - How the attack reads at a glance so players can distinguish between different attacks

4. **Damage & Vulnerability Indicators:** How does the boss visually communicate:
   - Where to hit (glowing weak points, exposed cores, flashing elements)
   - That damage was received (flash white, recoil animation, particle burst)
   - Health status (progressive visual damage, cracking armor, flickering energy)
   - Invulnerability periods (shield effects, transparency, color desaturation)

5. **Color Palette Strategy:** Define separate but related palettes for each phase, showing escalation through color intensity. Normal phase uses cooler or muted tones, later phases introduce reds, bright magentas, or harsh contrasts to communicate danger escalation.

6. **Defeat Sequence:** Describe the multi-frame death animation that rewards the player: dramatic explosion sequence, body part disintegration order, screen flash effects, any item drops or transformation reveals, and the emotional payoff of the visual spectacle.

7. **Technical Sprite Assembly:** If the boss exceeds single sprite limits, explain how to composite multiple sprite layers, which parts are separate sprites for independent animation, and how sprite priority/layering creates depth.