So that Skulking Geist is actually much stronger than the Fake Card posted earlier.
The Fake Card obviously wins you the game but it is only a 3/3 and only works mainly against Jade Druid and some janky shit: Gang Up / Thistle Tea.
Skulking Geist obviously ruins Jade Druid, but it is also able to remove some key cards from all classes:
Jade Druid: (Idol, Earthen Scales)
Evolve Shaman
Priest (PW:S, Binding Heal, Inner Fire, Potion of Madness)
Warrior: (Shield Slam, Whirlwind)
Mid/Control Hunter: (Hunter's Mark, Tracking)
Rogue: (Razorpetals, Toxins from Xaril, Hallucinations, Cold Blood)
Minimal annoyance:
Aggro Druid: (Mark of the Lotus)
Paladin: Secrets
Warlock: Soulfire, Mortal Coil