If Charm Person fails...

[Lysander]

Well, Charm person has one very useful aspect over simply killing them. It causes someone to help you out with all their ability, within whatever they're usually willing to do for friends.

You: Charm Person!
Enemy Wizard: *Charmed* Hey, I like you! You're all right.
You: Cool. Now cast all your buff spells on me and my allies. Now that we're friends you have no enemies, so you don't need them for yourself!
Enemy Wizard: Sure! *numerous buff spells*
You: Where do you keep your spellbook by the way? We should exchange spells while I'm in town.
Enemy Wizard: Ok! I have a decoy book filled with explosive runes locked up in my study. Pretty smart right? The real book is in an invisible bag of holding hanging from the ceiling.
You: Thanks buddy. Hey, why don't you take a nap. I'm throwing a party later and you're invited, so you should be well rested cause we're gonna dance all night!
Enemy Wizard: Ok. *closes eyes*
You: Nighty night.
Fighter Ally: *coup de grace*