Vow of the Indomitable is a Skill in Elden Ring. Vow of the Indomitable is a regular skill that can be found in Ashes of War and applied to shields.  Updated to Patch 1.07.

Elden Ring Vow of the Indomitable Guide, Notes & Tips

• This is an Ash of War Skill, associated with the Ash of War: Vow of the Indomitable.
• FP Cost: 20 on use
• This Skill is not Chargeable
• Upon activation, the user raises their shield into the air, enveloping themselves in a golden aura that makes them invulnerable for a brief period of time.
• Vow of the Indomitable has 4 start-up frames and damage immunity lasts for 30 iFrames (30 FPS)
• See Dodging for detailed information on the mechanic and a comparison of different dodging skills.