diff --git a/.claude/skills/backend-phase/SKILL.md b/.claude/skills/backend-phase/SKILL.md
new file mode 100644
index 0000000..fd0d5de
--- /dev/null
+++ b/.claude/skills/backend-phase/SKILL.md
@@ -0,0 +1,193 @@
+# Backend Phase Workflow Skill
+
+Manage the phased backend development workflow for Mantimon TCG.
+
+## Usage
+
+```
+/backend-phase              # Show current phase status and next task
+/backend-phase status       # Same as above
+/backend-phase next         # Show detailed info about next incomplete task
+/backend-phase start <id>   # Mark task as in-progress
+/backend-phase done <id>    # Mark task as complete (with tests)
+/backend-phase plan         # Create plan for next NOT_STARTED phase
+```
+
+## Files
+
+- **Master Plan:** `backend/PROJECT_PLAN_MASTER.json`
+- **Phase Plans:** `backend/project_plans/PHASE_N_*.json`
+
+## Workflow
+
+### Starting a New Phase
+
+1. Run `/backend-phase plan` to create the detailed plan for the next NOT_STARTED phase
+2. Review and adjust the generated plan
+3. Run `/backend-phase next` to see the first task
+
+### Working on Tasks
+
+1. Run `/backend-phase next` to see task details
+2. Run `/backend-phase start <task-id>` to mark it in-progress
+3. Implement the task following the details in the plan
+4. Write tests with docstrings explaining "what" and "why"
+5. Run `/backend-phase done <task-id>` when complete with passing tests
+
+### Completing a Phase
+
+When all tasks are complete:
+1. Update master plan status to "COMPLETE"
+2. Add completedDate
+3. Increment completedPhases count
+
+## Instructions
+
+When `/backend-phase` or `/backend-phase status` is invoked:
+
+1. **Read Master Plan**
+   ```
+   backend/PROJECT_PLAN_MASTER.json
+   ```
+
+2. **Find Current Phase**
+   - Look for first phase with `status: "in_progress"` or `status: "IN_PROGRESS"`
+   - If none, look for first phase with `status: "NOT_STARTED"`
+
+3. **Read Phase Plan**
+   ```
+   backend/project_plans/PHASE_N_*.json
+   ```
+
+4. **Display Status**
+   ```
+   ## Phase N: [Phase Name]
+
+   Status: IN_PROGRESS
+   Progress: X/Y tasks complete
+
+   ### Completed Tasks
+   - [x] TASK-001: Task name
+   - [x] TASK-002: Task name
+
+   ### Next Task
+   **TASK-003: Task name**
+   Category: services | Priority: 3
+   Dependencies: [TASK-001, TASK-002]
+
+   [Brief description from plan]
+
+   Run `/backend-phase next` for full details.
+   ```
+
+---
+
+When `/backend-phase next` is invoked:
+
+1. Find the first task where `completed: false` and all dependencies are met
+2. Display full task details:
+   ```
+   ## TASK-003: Task Name
+
+   **Category:** services
+   **Priority:** 3
+   **Estimated Hours:** 2
+   **Dependencies:** TASK-001, TASK-002 (all complete)
+
+   ### Description
+   [Full description from plan]
+
+   ### Implementation Details
+   - Detail 1
+   - Detail 2
+   - Detail 3
+
+   ### Files to Create/Modify
+   - `app/services/foo.py` (create)
+   - `app/main.py` (modify)
+
+   ### Notes
+   [Any notes from the plan]
+
+   ---
+   Run `/backend-phase start TASK-003` to begin work.
+   ```
+
+---
+
+When `/backend-phase start <task-id>` is invoked:
+
+1. Verify task exists and dependencies are met
+2. Log that work is starting (no file modification needed)
+3. Display the task details for reference
+4. Create Claude Code tasks using TaskCreate if task has multiple sub-items
+
+---
+
+When `/backend-phase done <task-id>` is invoked:
+
+1. Verify tests exist and pass for the task
+2. Update the phase plan JSON:
+   - Set `completed: true`
+   - Set `tested: true`
+3. Update `completedTasks` count in meta
+4. Check if phase is complete (all tasks done)
+5. If phase complete, prompt to update master plan
+
+---
+
+When `/backend-phase plan` is invoked:
+
+1. Find next NOT_STARTED phase in master plan
+2. Read existing phase plans for format reference
+3. Generate detailed plan based on:
+   - Phase description and deliverables from master plan
+   - Architecture patterns from CLAUDE.md
+   - Existing code patterns in the codebase
+4. Write to `backend/project_plans/PHASE_N_*.json`
+5. Update master plan status to "in_progress"
+
+## Task Schema
+
+```json
+{
+  "id": "GS-001",
+  "name": "Short task name",
+  "description": "What this task accomplishes",
+  "category": "services|schemas|infrastructure|auth|api|tests",
+  "priority": 1,
+  "completed": false,
+  "tested": false,
+  "dependencies": ["WS-001"],
+  "files": [
+    {"path": "app/services/game_service.py", "status": "create|modify"}
+  ],
+  "details": [
+    "Specific implementation step 1",
+    "Specific implementation step 2"
+  ],
+  "estimatedHours": 3,
+  "notes": "Optional implementation notes"
+}
+```
+
+## Rules
+
+1. **Dependencies First** - Never start a task with incomplete dependencies
+2. **Tests Required** - Every task must have tests before marking complete
+3. **Docstrings Required** - Test docstrings explain "what" and "why"
+4. **Commit Approval** - Never commit without user approval
+5. **One Task at a Time** - Focus on completing current task before starting next
+6. **Update Plans** - Keep plan files in sync with actual progress
+
+## Memory Integration
+
+After completing a task or phase, consider storing learnings:
+```bash
+python ~/.claude/skills/memorygraph/client.py store \
+  --type solution \
+  --title "Completed PHASE_4 GS-003" \
+  --content "Implemented forced action handling..." \
+  --tags "mantimon,backend,game-service" \
+  --importance 0.6
+```