Magnanimously is how you do something when you are being magnanimous: in a kind, generous way, especially toward someone you have just beaten or someone who is in a weaker position. After you win, you may speak magnanimously about the other side. You may magnanimously let them keep their pride. Same formal, slightly bookish feel as magnanimous. In everyday talk people are more likely to say “kindly” or “generously.” Use this word when you want that extra shade: not just kind, but kind from a position of strength.