Giant Trap Door Spider , : Exile this creature and target creature without flying that's attacking you.
Reglamento oficial (Oracle)
[2004-10-04]If Giant Trap Door Spider leaves the battlefield before its ability resolves, the ability will still resolve as normal. The targeted creature will be exiled.
[2004-10-04]If the targeted creature leaves the battlefield (or otherwise becomes an illegal target) before the ability resolves, the ability won’t resolve. Giant Trap Door Spider will remain on the battlefield.
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: Exile this creature and target creature without flying that's attacking you.