Most Minion powers are worded something like this:

Whenever a friendly character [some qualifier - a name, a keyword, etc.] is within 8 squares, [Minion character] can use [some power] and [some modifier].

What happens if the minion has 2 effects (like Charge and a +1 to attack) and they use the power to leave the 8-square radius of the source of the minion effect?

The Charge action would still resolve and the minion can make the attack. However, they would not get the modifier for the attack. Example:


IN the diagram above, Ulik is within 8 squares of the minion Rock Troll. Rock Troll's minion power lets him use Charge and gives him a +1 to his attack value (when he is wihtin 8 squares of Ulik). THe Rock Troll can use charge to get to square x in order to make an attack against the Target, but he would not be at +1 for his attack.