When casting Charm, do you need to declare the target unit's destination before resolution, and what are the legal destinations?

Ruling: When you put Charm on the chain, you must declare both the target enemy unit and its legal end destination.

Nuances:

• Your own base is not a legal destination for the charmed unit
• You can declare your opponent's base as the destination, but if the unit is at Vilemaw, Vilemaw's effect will prevent Charm from having any effect unless the unit moves to another battlefield before Charm resolves
• If the enemy unit is at Vilemaw, you cannot move it to your opponent's base, but you can move it to the other battlefield