You choose to protect yourself. A shimmering bright solid light emits from your skin, acting as a barrier to prevent damage. You are immune to all types of damage for the duration of the spell, but you are unable to take any actions, move,  use objects, take bonus actions, use any abilities or end the spell. You are essentially paralyzed for the duration of the spell. Non-damaging spells can still affect you. 

The spell can end if another magic user casts dispel magic or another equivalent spell successfully upon your person or if you take damage somehow (some abilities allow for the user to treat immunity as resistance for example).