Borg Cube is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Affinity for artifact creatures Whenever this Spacecraft enters or attacks, assimilate a creature card exiled with it. If you can't, exile up to one target creature. (To assimilate a card, put it onto the battlefield under your control with a +1/+1 counter. It's a Borg artifact creature and loses all other creature types.) Station 12+ | Artifact creatures you control have flying.