Skill Up Protocol Complete Guide
Shadow of the Tower to Mirage - Skill Materials Farming Strategy
Last updated: 2026-02-09
Complete guide to Skill Up Protocol Space in Arknights: Endfield with 5 stages (Shadow of the Tower to Mirage), enhanced finisher mechanics, team compositions, and sanity-efficient skill material farming for Protoprism/Protohedron.
* TL;DR - Key Points
- * Best early materials: Stage 1-2 (Shadow/Speck of the Tower) - 40-50 Sanity for 21-35 skill materials
- * Best material density: Stage 4-5 (Echoes/Mirage of the Tower) - 70-80 Sanity for 69-85+ skill materials
- * Mechanic: More enemy HP, more Stagger taken. Finishers deal much more DMG.
- * Location: The Hub, Valley IV - accessible mid-game (Authority Level 30+)
- * Total Sanity: 300 for all 5 stages
- * Primary rewards: Skill materials (Protoprism/Protohedron)
Contents
What is Skill Up Protocol Space?
Skill Up Protocol Space is a combat challenge mode located in The Hub and Valley IV that rewards skill leveling materials (Protoprism, Protohedron) for upgrading operator skills. It features mechanics that buff finisher damage while increasing enemy durability.
5 Stages
Shadow of the Tower to Mirage - 40-80 Sanity each
Skill Materials
21-85+ Protoprism/Protohedron per run
Finisher Bonus
Finishers deal greatly increased damage
Pro Tip: Finisher-Centric
Build teams around operators with strong finisher abilities. Finishers deal significantly more damage in this Protocol Space, making finisher-focused operators essential for efficient clears.
Complete Stage Overview
| Stage | Name | Sanity | Set A | Set B |
|---|---|---|---|---|
| 1 | Shadow of the Tower | 40 | 21 Skill Materials | N/A |
| 2 | Speck of the Tower | 50 | 35 Skill Materials | N/A |
| 3 | Remorse of the Tower | 60 | 50 Skill Materials | +10 bonus |
| 4 | Echoes of the Tower | 70 | 69 Skill Materials | +14 bonus |
| 5 | Mirage of the Tower | 80 | 85 Skill Materials | +17 bonus |
Mechanics Breakdown - Enhanced Finishers
Mechanic: Enemies have more HP and can take more Stagger. Finishers deal much more damage to enemies.
What This Means
- • Enemies have increased HP compared to other Protocol Spaces
- • Enemies can withstand more Stagger buildup
- • Finisher abilities deal significantly more damage than usual
- • Rewards building Stagger and using finishers strategically
How to Exploit
- • Build team with operators who have strong finisher abilities
- • Focus on building Stagger to unlock finishers
- • Time finisher usage for maximum impact
- • Use combo skills that lead into finishers
- • Build Stagger on priority targets
Pro Tip: Best Operators
Operators with powerful finisher abilities, Physical finishers (typically high burst damage), Heat operators (finisher specialists), and operators who enhance or extend finishers work best here.
Stage-by-Stage Walkthroughs
Stage 1: Shadow of the Tower (40 Sanity) - Easy-Medium
Unlocks immediately upon discovering protocol space
Basic enemies with moderate HP. Enhanced finisher damage active.
Strategy: Build finisher-focused team. Build Stagger to unlock finishers. Time finishers strategically. Use arena space to chain abilities.
Pro Tip:
Excellent Sanity efficiency. Run 2-3 times daily for consistent skill material income. Build team with strong finisher abilities and focus on Stagger buildup.
Stage 2: Speck of the Tower (50 Sanity) - Medium
Basic enemies with higher HP. Enhanced finisher damage active.
Strategy: Use Stage 1 team if clears are easy. Higher HP enemies require more Stagger. Finisher timing critical. Good Sanity efficiency.
When to Move: When Stage 1 clears are under 2 minutes and team builds Stagger consistently.
Stage 3: Remorse of the Tower (60 Sanity) - Medium-Hard
First stage with Set B option
Set A: 50 Skill Materials | Set B: +10 bonus
Strategy: Maximize finisher damage. Build Stagger on priority targets. Coordinate team for optimal finisher usage.
Stage 4: Echoes of the Tower (70 Sanity) - Hard
Set A: 69 Skill Materials | Set B: +14 bonus
Recommended: Operators Level 40+, E1 promoted team
Strategy: Strong team required. Maximize finisher damage against high HP. Stagger management on priority targets essential.
Stage 5: Mirage of the Tower (80 Sanity) - Very Hard
Set A: 85 Skill Materials | Set B: +17 bonus
Recommended: Operators Level 60+, E2-E3 promoted team
Strategy: Endgame content. Every finisher must count. Perfect Stagger management. Coordinate team and focus fire. Highest material density stage.
Team Composition Guide
| Slot | Role | Recommended | Priority |
|---|---|---|---|
| 1 | Main DPS | Finisher-focused operators | High |
| 2 | Stagger Builder | Physical/Heat Stagger specialists | High |
| 3 | Support | Healer or buffer operator | Medium |
| 4 | Tank | High DEF/HP operator | Medium |
Pro Tip: Finisher-Focused
The enhanced finisher mechanic rewards operators with powerful finisher abilities. Build a team around finisher-focused operators and prioritize Stagger buildup to unleash devastating finisher attacks.
When to Farm Skill Up
| Authority Level | Recommended Stage | Runs Per Day |
|---|---|---|
| 30-40 | Stage 1-2 | 2-3 |
| 40-50 | Stage 2-3 | 2-2 |
| 50-60 | Stage 3-4 | 1-2 |
| 60+ | Stage 4-5 | 1-2 |
Common Mistakes & How to Avoid Them
1. Running Stage 5 too early
Problem: Attempting Mirage of the Tower at Authority 30-40. Fix: Progress naturally. Stay on Stage 1-2 until operators Level 40+. Stage 5 requires E2-E3 team.
2. Not building for finishers
Problem: Using basic-attack operators when finishers deal greatly increased damage. Fix: Prioritize operators with strong finisher abilities. Build Stagger and use finishers strategically.
3. Ignoring Stagger management
Problem: Not building Stagger on priority targets. Fix: Focus Stagger buildup on key enemies. Time finishers for maximum impact.
4. Not timing finishers
Problem: Using finishers randomly instead of strategically. Fix: Build Stagger, then use finishers on priority targets for maximum damage efficiency.
Quick Reference Checklist
Frequently Asked Questions
How many stages are in Skill Up Protocol Space?
Skill Up Protocol Space has 5 stages: Shadow of the Tower (40), Speck of the Tower (50), Remorse of the Tower (60), Echoes of the Tower (70), and Mirage of the Tower (80) Sanity costs.
What rewards do Skill Up Protocol stages provide?
Stages reward Skill Materials (Protoprism/Protohedron). Stage 1: 21, Stage 2: 35, Stage 3: 50 (+10 bonus), Stage 4: 69 (+14 bonus), Stage 5: 85 (+17 bonus) skill materials.
What is the finisher mechanic in Skill Up Protocol?
Enemies have more HP and can take more Stagger. Finishers deal much more damage than usual. Build Stagger and use finishers strategically for maximum damage.
When should I start farming Skill Up Protocol?
Start around Authority Level 30+ with Stage 1-2. Progress to Stage 3+ when operators reach Level 40-50 and you have finisher-focused operators.
Which operators work best in Skill Up Protocol?
Operators with powerful finisher abilities excel. Physical finishers, Heat operators, and operators who enhance or extend finishers are ideal. Stagger builders help unlock finishers.