Reference summary · Keyword · Rules Tome 2.0.8 § 602.7
Unique
A same-name card you control in play with Unique prevents another copy entering play.
How it works
Rule explanation
Unique applies to cards, not just Characters. When a card would enter play, it cannot enter if you already control a card with the same name in play that has Unique, even if the incoming card lacks Unique. You may bring in a Unique card if the same-name card already in play does not have Unique. You may not start with more than one copy of the same Unique card. The restriction is not continuously rechecked afterward.
At the table
Example
If your existing copy has lost Unique, an incoming Unique copy is not blocked by that existing card. If the existing copy has Unique, another same-name copy cannot enter.
Watch for this
Common mistake
Check Unique on the card already in play, not either copy. Unique is not the one-copy deck limit; Epic is.