Promotions ProtocolComplete Guide

Tacit Brook to Maelstrom - Promotion Materials Farming Strategy

Last updated: 2026-02-09

Complete guide to Promotions Protocol Space in Arknights: Endfield with 5 stages (Tacit Brook to Maelstrom), SP generation mechanics, team compositions, and sanity-efficient farming for Basic and Intermediate Promotion Materials.

*TL;DR - Key Points

* Best early promos: Stage 1-2 (Tacit Brook/Canal) - 40-50 Sanity for Basic materials
* Best material density: Stage 4-5 (Undercurrent/Maelstrom) - 70-80 Sanity for Intermediate materials
* Mechanic: Natural SP recovery very slow. Skill-based SP recovery greatly increased.
* Location: The Hub - accessible mid-game (Authority Level 25+)
* Total Sanity: 300 for all 5 stages
* Primary rewards: Promotion materials (Basic/Intermediate)

What is Promotions Protocol Space?

Promotions Protocol Space is a combat challenge mode located in The Hub that rewards promotion materials for elevating operator tiers (E1, E2, etc.). It's the primary source of upgrade materials for operator advancement.

5 Stages

Tacit Brook to Maelstrom - 40-80 Sanity each

Basic Materials

8-34 Basic Promotion Materials per run

Intermediate Materials

8-14 Intermediate Materials (Set B, Stages 3-5)

Pro Tip: SP Mechanic

Natural SP recovery is very slow here. Build teams with multi-hit and combo-skill operators who generate SP actively through attacking and skill usage. Passive operators will struggle.

Complete Stage Overview

Stage	Name	Sanity	Set A	Set B
1	Tacit Brook	40	8 Basic Materials	N/A
2	Tacit Canal	50	14 Basic Materials	N/A
3	Tacit Mere	60	20 Basic Materials	8 Intermediate
4	Tacit Undercurrent	70	27 Basic Materials	11 Intermediate
5	Tacit Maelstrom	80	34 Basic Materials	14 Intermediate

Mechanics Breakdown - SP Recovery Altered

Mechanic: Natural SP recovery is much slower than normal. Skill-based SP recovery (from hitting enemies, combos, etc.) is greatly increased.

What This Means

• Operators naturally gain SP very slowly over time
• Using skills generates SP much faster than usual
• Active playstyle required - cannot rely on passive SP generation
• Need operators with good SP generation skills

How to Exploit

• Build team with operators who have strong SP generation abilities
• Prioritize skill usage and hitting enemies
• Avoid passive operators who rely on natural SP recovery
• Focus on high-attack-speed operators for consistent SP gain

Pro Tip: Best Operators

Multi-hit operators (more hits = more SP), Combo-skill focused operators (combo skills generate SP), Physical/Heat operators (typically attack speed focused), and operators with SP-generating passive abilities work best here.

Stage-by-Stage Walkthroughs

Stage 1: Tacit Brook (40 Sanity) - Easy

Unlocks immediately upon discovering protocol space

Basic enemies, 2-3 waves

Strategy: Build SP-generation team with multi-hit and combo-skill operators. Use skills as soon as available. Active playstyle required.

Pro Tip:

Excellent Sanity efficiency for Basic Promotion Materials. Run 2-3 times daily for E1 materials. Bring operators with strong SP generation.

Stage 2: Tacit Canal (50 Sanity) - Easy-Medium

Same enemies as Stage 1 with more HP

Strategy: Use Stage 1 team if clears are easy. Focus on SP generation. Active playstyle still essential.

When to Move: When Stage 1 clears are under 2 minutes and team generates SP consistently.

Stage 3: Tacit Mere (60 Sanity) - Medium

First stage with Set B option

Set A: 20 Basic Promotion Materials

Set B: 8 Intermediate Promotion Materials

Strategy: Maximize SP generation with multi-hit team. Choose Set B when progressing to E2.

Stage 4: Tacit Undercurrent (70 Sanity) - Hard

High HP enemies, 3-4 waves

Set A: 27 Basic, Set B: 11 Intermediate

Recommended: Operators Level 40+, E1 promoted team

Strategy: Build SP-heavy team with strong generation. Set B excellent for E2+ materials.

Stage 5: Tacit Maelstrom (80 Sanity) - Very Hard

Very high HP enemies, 4-5 waves

Set A: 34 Basic, Set B: 14 Intermediate

Recommended: Operators Level 60+, E2-E3 promoted team

Strategy: Maximize SP generation. Aggressive playstyle required. Only attempt when consistently clearing Stage 4.

Team Composition Guide

Slot	Role	Recommended	Priority
1	Main DPS	Multi-hit Physical/Heat operators	High
2	Sub DPS	Combo-skill focused operator	High
3	Support	Healer or SP-buffer operator	Medium
4	Tank	High DEF/HP operator	Medium

Pro Tip: SP Generation Focused

The slowed natural SP recovery demands an active playstyle. Build a team around operators who generate SP through attacking and using skills:

• Multi-hit attackers (more hits = more SP)
• Combo-skill specialists (combo abilities generate SP)
• Physical/Heat operators (typically high attack speed)
• Operators with SP-generating passives

When to Farm Promotions

Authority Level	Recommended Stage	Runs Per Day
25-30	Stage 1-2	2-3
30-40	Stage 2-3	2-2
40-50	Stage 3-4	1-2
50+	Stage 4-5	1-2

Common Mistakes & How to Avoid Them

1. Running Stage 5 too early

Problem: Attempting Tacit Maelstrom at Authority 25-30. Fix: Progress naturally. Stay on Stage 1-2 until operators Level 30-40. Stage 5 requires E2-E3 team.

2. Ignoring Set B options

Problem: Always choosing Set A when Set B might better suit your needs. Fix: Check your Promotion Material inventory. Choose Set B if you need Intermediate materials for E2+.

3. Not building for SP generation

Problem: Using passive operators when natural SP recovery is very slow. Fix: Prioritize multi-hit and combo-skill operators. Active playstyle required.

4. Being passive with SP

Problem: Playing like normal stages, not accounting for slowed natural SP recovery. Fix: Be aggressive! Attack constantly and use skills. Passive play won't work.

Quick Reference Checklist

Authority Level 25-30

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Run Stage 1 (Tacit Brook) 2-3 times daily (40 Sanity)

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Use multi-hit operator team for SP generation

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Focus on Basic Promotion Materials for E1 progression

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Avoid Stage 3+ until team Level 30+

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Active playstyle - attack constantly to generate SP

Authority Level 30-40

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Add Stage 2 (Tacit Canal) to rotation (50 Sanity)

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Push to Stage 3 if team clears Stage 2 easily

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Consider Set B reward at Stage 3 if needing Intermediate materials

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Build team with stronger SP generation

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E1 promote key operators before Stage 3+

Authority Level 40-50

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Push to Stage 3-4 when operators Level 35+ and E1 promoted

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Choose Set A vs Set B based on current needs

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Build multi-hit team for consistent SP generation

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Focus on Intermediate Promotion Materials for E2

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Balance Promotions with Operator EXP farming

Authority Level 50+

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Push to Stage 4-5 when operators Level 50+, E2-E3 promoted

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Prioritize Stage 5 for best material density

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Only run Stage 5 when clears are consistent

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Build max SP-generation team for Stage 5

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Shift focus as promotion needs are met

Frequently Asked Questions

How many stages are in Promotions Protocol Space?

Promotions Protocol Space has 5 stages: Tacit Brook (40), Tacit Canal (50), Tacit Mere (60), Tacit Undercurrent (70), and Tacit Maelstrom (80) Sanity costs.

What rewards do Promotions Protocol stages provide?

Stages 1-2 drop Basic Promotion Materials. Stages 3-5 offer Set A (Basic) and Set B (Intermediate) Promotion Material options. Stage 5 Set B provides 14 Intermediate Promotion Materials.

What is the SP mechanic in Promotions Protocol?

Natural SP recovery is much slower than normal. Skill-based SP recovery (from hitting enemies, combos) is greatly increased, requiring an active playstyle with multi-hit and combo-skill operators.

When should I start farming Promotions Protocol?

Start around Authority Level 25+ with Stage 1-2 for E1 materials. Progress to Stage 3+ when operators reach Level 30-40 and are E1 promoted for Intermediate materials.

Which operators work best in Promotions Protocol?

Multi-hit Physical/Heat operators and combo-skill specialists excel because they generate SP the fastest. Avoid passive operators who rely on natural SP recovery.