Tarnished Seal Abilities in Mortal Shell are covered in this page. Tarnished Seal has 4 Tarnished Seal Abilities that can be used and swapped during battle by using Resolve. In order to acquire a Tarnished Seal Ability, players will need to find the required Gland and bring it back to The Old Prisoner at the Fallgrim Tower. Each Gland provides a different Tarnished Seal Ability. Note that the third Gland that will be given to The Old Prisoner will not unlock it's corresponding Seal Ability, so the player will need to start NG+ and play the corresponding region again, this time not as the third destination to unlock it.
All Tarnished Seal Abilities in Mortal Shell

Seal Infusion - Healing
Spend 1 Resolve to perform an Empowered Riposte which deals damage to the enemy and heals your character.

Seal Infusion - Inflamed
Spend 1 Resolve to perform an Empowered Riposte. Your riposte will attach a charged larva to your enemy which explodes.

Seal Infusion - Knotted
Spend 1 Resolve to perform an Empowered Riposte. Your riposte will throw all enemies around you into the air and slow their time.

Seal Infusion- Crystalline
Spend 1 Resolve to perform an Empowered Riposte. Your riposte will unleash your foundling dealing very high damage