Jingasa of the Fortunate Soldier
Wondrous Item, very rare (requires attunement)
This conical iron jingasa, or war hat, grants the wearer a +1 bonus to AC. When struck by a critical hit or sneak attack, the wearer can use a reaction to negate the critical hit or sneak attack. The damage is instead rolled normally.
This ability functions only once per long rest, though the jingasa continues to grant its deflection bonus even after the other ability is expended.