diff --git a/README.md b/README.md
index 088838d..dd70740 100644
--- a/README.md
+++ b/README.md
@@ -225,6 +225,131 @@ EOF
 python scripts/analyze_decks.py --collection collection_hydrated/deck.json --deck-dir decks/
 ```
 
+---
+
+## Runbook: Update Your Collection
+
+### Scenario 1: Add New Cards (Single File)
+
+If you opened new packs and want to add cards:
+
+```bash
+# 1. Create a new file with the new cards
+cat > collection/new_cards_2026-02-20.txt << 'EOF'
+1 Bre of Clan Stoutarm (ECL) 8
+3 Mulldrifter (ECC) 67
+1 Sol Ring (ECC) 57
+EOF
+
+# 2. Hydrate the new file (merges into existing cache)
+python hydrate.py hydrate collection/new_cards_2026-02-20.txt -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 2: Add Cards to Existing File
+
+```bash
+# Append to existing collection file
+echo "1 The Reaper, King No More (ECC) 4" >> "collection/Box1 2026-01-30.txt"
+
+# Re-hydrate that file
+python hydrate.py hydrate "collection/Box1 2026-01-30.txt" -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 3: Merge Multiple Collection Files
+
+If you have multiple files to combine:
+
+```bash
+# Hydrate each file separately (cache persists)
+python hydrate.py hydrate collection/Box1.txt -o collection_hydrated/ -c card_cache.json
+python hydrate.py hydrate collection/Box2.txt -o collection_hydrated/ -c card_cache.json
+
+# Note: Each run overwrites deck.json. To merge, combine files first:
+cat collection/Box1.txt collection/Box2.txt > collection/combined.txt
+python hydrate.py hydrate collection/combined.txt -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 4: Re-hydrate Entire Collection
+
+If cache is corrupted or you want fresh data:
+
+```bash
+# Option A: Keep cache, just re-run
+python hydrate.py hydrate collection/combined.txt -o collection_hydrated/ -c card_cache.json
+
+# Option B: Clear cache and fetch fresh (slow, ~100ms per unique card)
+rm card_cache.json
+python hydrate.py hydrate collection/combined.txt -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 5: Update After Set Release
+
+When a new set releases and you want to add those cards:
+
+```bash
+# 1. Add new set cards to collection file
+echo "# Lorwyn Eclipsed - 2026-01-23" >> collection/my_collection.txt
+cat collection/new_ecl_cards.txt >> collection/my_collection.txt
+
+# 2. Hydrate (cache speeds up existing cards, fetches new ones)
+python hydrate.py hydrate collection/my_collection.txt -o collection_hydrated/ -c card_cache.json
+
+# 3. Verify new cards are present
+python -c "
+import json
+cards = json.load(open('collection_hydrated/deck.json'))
+print(f'Total unique cards: {len(cards)}')
+"
+```
+
+### Collection File Format
+
+```
+# Comments start with #
+# Format: <count> <Card Name> (<Set Code>) <Collector Number>
+
+1 Sol Ring (CMA) 1
+3 Birds of Paradise
+1 Eternal Witness (EMA) 183
+
+# Set code and collector number are optional but recommended
+# They help Scryfall find the exact printing
+```
+
+### Troubleshooting
+
+**Card not found:**
+```
+Error fetching 'Some Card Name': HTTP 404
+```
+→ Check spelling, or try without set code. Use the exact name from Scryfall.
+
+**Duplicate cards:**
+If the same card appears multiple times in your file, they're stored separately. Dedupe first:
+```bash
+# Combine duplicates
+python -c "
+from collections import Counter
+cards = Counter()
+with open('collection/my_cards.txt') as f:
+    for line in f:
+        line = line.strip()
+        if line and not line.startswith('#'):
+            parts = line.split(None, 1)
+            if parts:
+                count = int(parts[0]) if parts[0].isdigit() else 1
+                name = parts[1] if len(parts) > 1 else parts[0]
+                cards[name.split('(')[0].strip()] += count
+for name, count in sorted(cards.items()):
+    print(f'{count} {name}')
+" > collection/deduped.txt
+```
+
+**Slow hydration:**
+- First run fetches all cards (~100ms each)
+- Subsequent runs use cache (instant)
+- 866 unique cards ≈ 87 seconds first run
+
 ## Collection Stats
 
 - **Total cards:** 1209
diff --git a/docs/templates/README.template.md b/docs/templates/README.template.md
index a2b6ca2..ee8bb51 100644
--- a/docs/templates/README.template.md
+++ b/docs/templates/README.template.md
@@ -220,6 +220,131 @@ EOF
 python scripts/analyze_decks.py --collection collection_hydrated/deck.json --deck-dir decks/
 ```
 
+---
+
+## Runbook: Update Your Collection
+
+### Scenario 1: Add New Cards (Single File)
+
+If you opened new packs and want to add cards:
+
+```bash
+# 1. Create a new file with the new cards
+cat > collection/new_cards_2026-02-20.txt << 'EOF'
+1 Bre of Clan Stoutarm (ECL) 8
+3 Mulldrifter (ECC) 67
+1 Sol Ring (ECC) 57
+EOF
+
+# 2. Hydrate the new file (merges into existing cache)
+python hydrate.py hydrate collection/new_cards_2026-02-20.txt -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 2: Add Cards to Existing File
+
+```bash
+# Append to existing collection file
+echo "1 The Reaper, King No More (ECC) 4" >> "collection/Box1 2026-01-30.txt"
+
+# Re-hydrate that file
+python hydrate.py hydrate "collection/Box1 2026-01-30.txt" -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 3: Merge Multiple Collection Files
+
+If you have multiple files to combine:
+
+```bash
+# Hydrate each file separately (cache persists)
+python hydrate.py hydrate collection/Box1.txt -o collection_hydrated/ -c card_cache.json
+python hydrate.py hydrate collection/Box2.txt -o collection_hydrated/ -c card_cache.json
+
+# Note: Each run overwrites deck.json. To merge, combine files first:
+cat collection/Box1.txt collection/Box2.txt > collection/combined.txt
+python hydrate.py hydrate collection/combined.txt -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 4: Re-hydrate Entire Collection
+
+If cache is corrupted or you want fresh data:
+
+```bash
+# Option A: Keep cache, just re-run
+python hydrate.py hydrate collection/combined.txt -o collection_hydrated/ -c card_cache.json
+
+# Option B: Clear cache and fetch fresh (slow, ~100ms per unique card)
+rm card_cache.json
+python hydrate.py hydrate collection/combined.txt -o collection_hydrated/ -c card_cache.json
+```
+
+### Scenario 5: Update After Set Release
+
+When a new set releases and you want to add those cards:
+
+```bash
+# 1. Add new set cards to collection file
+echo "# Lorwyn Eclipsed - 2026-01-23" >> collection/my_collection.txt
+cat collection/new_ecl_cards.txt >> collection/my_collection.txt
+
+# 2. Hydrate (cache speeds up existing cards, fetches new ones)
+python hydrate.py hydrate collection/my_collection.txt -o collection_hydrated/ -c card_cache.json
+
+# 3. Verify new cards are present
+python -c "
+import json
+cards = json.load(open('collection_hydrated/deck.json'))
+print(f'Total unique cards: {len(cards)}')
+"
+```
+
+### Collection File Format
+
+```
+# Comments start with #
+# Format: <count> <Card Name> (<Set Code>) <Collector Number>
+
+1 Sol Ring (CMA) 1
+3 Birds of Paradise
+1 Eternal Witness (EMA) 183
+
+# Set code and collector number are optional but recommended
+# They help Scryfall find the exact printing
+```
+
+### Troubleshooting
+
+**Card not found:**
+```
+Error fetching 'Some Card Name': HTTP 404
+```
+→ Check spelling, or try without set code. Use the exact name from Scryfall.
+
+**Duplicate cards:**
+If the same card appears multiple times in your file, they're stored separately. Dedupe first:
+```bash
+# Combine duplicates
+python -c "
+from collections import Counter
+cards = Counter()
+with open('collection/my_cards.txt') as f:
+    for line in f:
+        line = line.strip()
+        if line and not line.startswith('#'):
+            parts = line.split(None, 1)
+            if parts:
+                count = int(parts[0]) if parts[0].isdigit() else 1
+                name = parts[1] if len(parts) > 1 else parts[0]
+                cards[name.split('(')[0].strip()] += count
+for name, count in sorted(cards.items()):
+    print(f'{count} {name}')
+" > collection/deduped.txt
+```
+
+**Slow hydration:**
+- First run fetches all cards (~100ms each)
+- Subsequent runs use cache (instant)
+- 866 unique cards ≈ 87 seconds first run
+
 ## Collection Stats
 
 {{COLLECTION_STATS}}