If I was able to "escape" Dark Impostor (by using something like Underworld Breach ), would it gain all activated abilities of the cards exiled via the escape cost?
No. The phrase "cards exiled with [this]" has no interactivity or combo potential, ever. That phrase in any ability just makes that ability linked to whatever other ability on that card can exile objects.
That ability on Dark Impostor *only* refers to cards exiled as a result of resolutions of the other activated ability, on that specific Dark Impostor permanent so long as it has remained on the battlefield. (CR 406.6)
Also consult CR 607. Linked Abilities, particularly 607.2a.
That ability on Dark Impostor *only* refers to cards exiled as a result of resolutions of the other activated ability, on that specific Dark Impostor permanent so long as it has remained on the battlefield. (CR 406.6)
Also consult CR 607. Linked Abilities, particularly 607.2a.
edit: added citation
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