Carl's ring, which flashes and warms as it partially blocks the effects of soul poisoning.
When the burning cramp of Soul Poisoning hits Carl in the alley, his Emberus ring flashes and starts to get warm. The health menu explains why: 'The effects of this condition are being partially blocked by your Pauper's ring of the Steadfast Emberus.'
Partially is the operative word. The condition is still worsening, still causing jolts of pain, and still has additional effects waiting to be revealed if he does nothing. The ring buys him time to reach a corpse and discharge Daughter's Kiss, no more. It also serves as a warning light - the flash and the heat are how he learns something is wrong before he even opens his menus.
A ring on Carl's hand that flashes and grows warm when it is absorbing a condition's effects.
A defensive item that softens soul poisoning enough for Carl to survive his own oversight, and doubles as an early-warning indicator.