How to Get Shadow Mantle in Deltarune
Written by Aarav Agarwal
If you want the Shadow Mantle in Deltarune Chapter 3, you’ll need to S-rank both of Tenna’s minigame boards and unlock the hidden version of each.
This leads to a secret room, several strange dungeon variants, and eventually, a powerful boss. Beating that boss gives you the Shadow Mantle... and sets you up for Chapter 3’s true final encounter.
Step 1: S Rank Both Boards
You must get S Rank on both minigame boards (the ones tied to Tenna’s TV games). You’ll know you’ve done it when the green room unlocks the “S-Rank Door.”
To improve your rank:
Episode 1: Get all 4 keys (not just 3)
Episode 2: Collect 4 photos (including Lancer at the geyser) and find moss patches
Some players mention a bribe option to skip this, but it’s not consistent.
Step 2: Enter the S-Rank Door
Once you’ve earned S-rank, head to the S-Rank Changing Room (the green room with the big door). Each time you enter after a board, you’ll unlock a new variant dungeon. You’ll need to beat 3 unique game variants total to unlock the Shadow Mantle.
Each one is slightly twisted and more aggressive than the originals.
Step 3: Complete All 3 Minigames
Game 1: Explore, level up, then break through trees in the top-right forest area to find a chest with the Ice Key.
Game 2: Use the Ice Key in the snowy area accessed by raft. You’ll meet an NPC who follows and helps you. Use their ice blasts to freeze enemies into movable blocks for puzzles. Eventually, you get another key.
Game 3: Enter the final S-rank minigame. Explore until you reach the boss fight. You can even attack in-game Susie and Ralsei (unclear if this affects story).
Step 4: Defeat the Boss
The boss is fast, and full of tricks.
Tips:
Focus on dodging during the orange orb attack
When the boss fires bombs, you can press offense
Minions drop heals, so clear them out early
In the final phase, dodge meteors and attack the black version of the boss, not red
Win the fight and you’ll be rewarded with the Shadow Mantle, a defensive item that reduces damage and prepares you for the next secret.
Step 5: Beat the Roaring Knight (Optional Secret Boss Fight)
If you have the Shadow Mantle equipped when you reach the Roaring Knight (after Tenna), you can trigger a hidden final boss phase. The Knight drops a Shadow Crystal and a Black Shard, a weapon for Kris.
Without the Shadow Mantle, the fight would be brutal. With it... still brutal, but survivable.
Final Blurb
Getting the Shadow Mantle means beating some of the hardest content in Chapter 3, and unlocking this chapter’s secret boss.
FAQ
Q: Can you get the Shadow Mantle without S ranks?
No, S ranks on both Tenna boards are required to access the S-Rank door.
Q: Do I need to beat the boss in one run?
No, if you die, Gaster will let you retry the boss fight.
Q: Is the Roaring Knight the secret boss?
Pretty much. It’s the closest Chapter 3 gets to a true endgame challenge once the Mantle is equipped.
Q: What does the Shadow Mantle actually do?
It reduces damage in key fights and may influence future chapter triggers or unlocks.
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