Living Dead
Ability Instant 300s
Grants the effect of Living Dead.
Your HP can be reduced below 0 without being KO'd under the effect of Living Dead. The negative HP can be healed as normal HP. If your HP is below 0 before the Walking Dead timer runs out, you will be KO'd.
Living Dead Duration: 10s
Additional Effect: Restores HP with each weaponskill successfully delivered or spell cast
Cure Potency: 1500

Superbolide
Ability Instant 120s
Reduces HP to 1 and creates a barrier which nullifies damage equaling the reduced HP.
Duration: 15s

Yes, this is not an invul. However, they gain another ability:

Role Reversal
Ability Instant 360s
Converts all damage taken into healing and all healing received into damage.
Duration: 10s