Uncanny Dodge (Grim Alteration)
From D&D Wiki
Harnessing the otherworldly energy while Transformed, he gains an awareness of his surrounding that allows him to dodge out of danger.
Description: He retains his Dexterity bonus to AC (if any) even if he is caught flat-footed or struck by an invisible attacker. However, he still loses his Dexterity bonus to AC if immobilized.
Special: If a grim already has Uncanny Dodge from a different class, he automatically gains Improved Uncanny Dodge instead while Transformed.