I laughed a little when I read about the charm and waiting until the whole unit was dead. The only possible way for this work would be in a small unit of TG without a Slann. A big unit of TG w/ a Slann basically means that for him to be the only one left, the Slann must be dead. At that point, if your unit of TG was wiped out (save the champ), your Slann was dead, things are looking pretty bad for you as the LM player. No doubt, you opponent has some form of magical defense against this charm since he doesn't have to worry about dispelling your Slann's spells.
In a small unit of TG (say 10?), this seems like it could work. It would be a long shot because you'd have to have enough magic available to prevent your opponent from dispelling the move, after the TG rallied and was able to use this move. Keep in mind that your magic must come from skink priests because using a Slann means that he has to join the unit of TG. Once your magic phase allows this move to go off, you'll have to figure out a way whittle 9 temple guard off the unit without getting the champion killed (a proverbial moonshot). Remember, that your magic must remain viable throughout this process so that you can burn your opponents DD. Now, after all that you're ready to fly your lone TG into something and smash it. At this point though, all the warmachines and casters should be dead. If they're not, then chances are, you're not looking like your going to get a win anyways.
In theory, this idea sounds pretty good. I don't think its a good gamble to spend points on, because the payoff in game is not very beneficial (Lone, flying TG?) as compared to the work and luck needed to pull it off. It's a very entertaining idea though.
****This is the tread that won't die****