Mysterious Orb
by Evan Lorentz

The power to relocate only one personnel may not seem like much at first, but when it can be any personnel, from any location, to any other location, and cannot be nullified by any means... well, then you've got something. Acquire a Mysterious Orb quickly from Q's Planet (or with HQ: Return Orb to Bajor, without even having to complete a mission), and you can move The Emissary to the Gamma Quadrant without even using the Bajoran Wormhole. Unless your opponent can produce their own way of getting to the Gamma Quadrant, they will not be able to interfere with your plans there -- Colony Preparations, for example.

Mysterious Orb is also one of the best artifacts a Borg player could ask for. You can use it to single out the best choice for a counterpart, and relocate them straight to your own Borg ship. Battle will of course immediately result in the "abduction" of the counterpart, who you can quickly strap to the Assimilation Table -- all without fear of retaliation by your opponent.

Combo:
Mysterious Orb + your best dilemma combos: Remove a personnel with a critical skill needed for your dilemmas before your opponent attempts the mission.