Alright, so summoning and binding a faerie servant in his apartment might be a bad idea. But Strange is a giant hypocrite who occasionally doesn't think things through and dammit, he just signed the divorce papers a few days ago, so he's still a bundle of anger and nerves and bad decisions. He had already picked out the faerie in question: Childermass, one who served the Rose Queen and who rumors say was very good at getting information and finding things out. Of course, he was a changeling and not a legitimate faerie...but beggars can't be choosers. Best to bind something lesser to his will and work his way up.

So congrats Childermass, you're now stuck in this magic circle thanks to an accountant. Strange's apartment is the sort that's desperately trying to look nicer than it actually is and, based on the boxes around, he's obvious not finished moving in yet. Strange himself looked a bit frazzled in his loosened necktie and dress shirt with the sleeves rolled up. Still, he's all business as he holds his hands out towards the magic circle (which is glowing a faint shade of blue) and casts the spells in a strong voice. A quick phrase in Latin, one in Greek, one in English that straight up tells Childermass that this is a binding spell.

The magic circle and the set-up takes most of the magical energy. The actual spell is brief yet powerful. Once the spell is finished being cast, Strange looks over at Childermass with a far too smug smirk. "You can step out of the circle, if you wish. And I wouldn't try anything rash. I've worked a Charm of Retribution in the framework of the binding circle, so whatever you try to do to me will be reflected back on you tenfold."

It's more like twofold. But like hell he's going to admit that to his newly bound faerie servant (God he is so pumped that the spell worked).