Margit’s Shackles are an item you can find in Elden Ring to make it easier to fight Margit’s boss, Omen Fallen. However, this item seems to be good for a lot more as it can help you discover hidden illusory walls and stop fire traps.
Margit’s Shackles can stop the boss for a few seconds when activated, but its usefulness doesn’t end after the enemy is defeated.
NateThePunk2 on Reddit is one of those who discovered that it can also cause the nearby hidden wall to disappear.
The gist is that the item sends out a kind of invisible shockwave that stuns Margit if he is within a certain range. The same shockwave emanates from the player, revealing illusory walls and stopping fire traps. The radius of the shackles is quite large, which makes it easier, instead of hitting / somersaulting into every wall.
Margit’s Shackles can be obtained while you’re completing Patchwork’s questline, and getting them is especially useful if Margit, the game’s first main boss, proves too much of a challenge.