As with all things, the trick to chase the magic away is to implement them. I recently made a little term rewriting library using racket/match syntax but with the pattern/templates specifiable at runtime. Ellipses were a bit confusing to begin with but when you break list patterns down into cons pairs + a cons-like pattern binary combinator to represent ellipses, it started making sense. The unexpected thing for me was that I thought nested ellipses were going to be the tough part, but it turns out they actually just... work.