Locked Shackle is a trinket in Fiend Folio, a mod for The Binding of Isaac.

+1 damage.
+0.35 tears.
+1 range.
+0.16 shot speed.
+1 luck.

Cannot be dropped manually, unless replaced with Paper Clip.

Picking up a key has a 25% chance to use the key to remove the trinket along with all aforementioned stats.

Picking up one of the following trinkets will double the current stats, keeping them permanently while also removing the trinket. Some of the trinkets have special effects when picked up:
• Blue Key → charms all blue enemies in Blue Rooms
• Crystal Key → opens all surrounding Red Rooms in the current room, and the next 2 rooms
• Gilded Key → spawns 3 Locked Chests
• Rusted Key → no special effect
• Store Key → spawns 5 Pennies
• Strange Key → activates Pandora's Box
• Wackey → boosts the stats by x1.3 instead of x2, and uses Three of Spades

The following special synergies and interactions for Locked Shackle have been documented.

* Note that not all possible synergies and interactions are listed here.

• Check out the trinket description on the mod's external Wiki.
• Download Fiend Folio from the Steam Workshop.