[ Matt steps forward, and in accordance, Astarion leans back, his frame hanging in that reclined state for a moment before he slips out of Matt's immediate periphery, treading quietly to stop a few steps behind him before dispelling the illusion. ]

I suppose it's a trade-off, [ he says, as he brushes off his hands (despite having absolutely no reason to do so — it's just a little extra melodrama). ] I don't need any components, but my ability to channel magic is— limited. It isn't as though I can cast spells as many times as I'd like. And more difficult spells take more effort.

[ Or so goes the most reasonable explanation for spell slots one can muster without breaking the fourth wall. ]

Some people just use scrolls. It's an easy in to more complicated magic, if also, well, limited by how many you have.