This sounds like it was designed for Kōhaku Narukami and his Geist weakness Weeping Yurei. Although an annoying weakness if drawn at the wrong moment, you can pretty much control when the thing attacks you with a Kōhaku deck, and assuming you were investigating anyway Oculus Mortuum helps you getting the clue and at the same time stinging the little hit-and-runner. I see this as a true blessing regarding its keywords and the fact that the last damage will interrupt and negate the attack.
Supporto. Hand
Oggetto. Strumento. Occulto.
Costi: 3.
Utilizzo (0 prove).
Dopo che hai sigillato, annullato o ignorato un segnalino caos, esaurisci l'Oculus Mortuus: Colloca 1 prova su di esso.
Quando un nemico attacca un investigatore nel tuo luogo, spendi 1 prova ed esaurisci l'Oculus Mortuus: Scopri 1 indizio nel tuo luogo. Se quel nemico possiede il tratto Geist, infliggigli 1 danno.

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Reviews
I can only assume the TDC campaign box has some kind of Geist enemies in it that can be damaged by this, but it's straight up bad in runs of Carcosa or Circle Undone, which have Geists that resist most types of damage. Maybe particularly bad in TCU, where the game practically expects you to cancel certain treacheries to balance the game.