Alchemy. It's a science, from my world, that's been in most of my memories... 'cept I did it differently in most of 'em. First time I've been able to actually do it here! It lets me change things, long as I know what they're made of.
Don't think I can do anything bigger'n this, it's taking a lot of work... but I bet I could fix something if it was broken, or make something useful.