What is this wizardry of which you speak?
Keep it sealed and dry and it stays nice in the powder form. I have poured it into active fermentations before with no ill effects. In fact, I have placed in comps with beers having this addition. I didn't believe it either until my buddy told me he tried it and I sampled his beer and thought it was good. Tried it out myself and was pleasantly surprised.
Not something I would recommend all the time, but in a pinch it can help you gain back those missing gravity points not made up in the kettle.
EDIT - I would only add it this way to an already active fermentation where the yeast have already taken hold
of the wort.