Can a player use Charm to move an opponent's unit into their own base, and if so, does combat occur there?

Ruling: No, a unit cannot appear in the opponent's base for any reason. Combat is a term tied to battlefields only, so no combat would occur in a base regardless.

Nuances:

• It is legal to Charm an enemy unit to that unit's own base (the base of the unit's owner)
• Charm can move a unit from battlefield to battlefield without requiring the Ganking ability (Ganking is only related to standard moves)