A vampire with no circle designation is in his own unique circle. Vampires with the same name (eg. The Embrace, non-unique vampires) do not share a circle by default, each has his own circle of one by default.
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Shell Game
Only usable when the action is announced.
Lock X other ready Blood Brothers you control of the same circle as this one to give this Blood Brother +X stealth (even if stealth is not yet needed). If the action is successful, you may unlock one of those Blood Brothers.
As above, but unlock an additional one of those Blood Brothers if the action is successful.
Rulings
Must be played (as well as other "as the action is announced" action modifiers) before action modifiers that are not explicitly played "as the action is announced" (e.g., Conditioning).
Replace the action card (if any) before playing it.