While brainstorming natural two-colour effects, it occurred to me this combination fit really naturally, and was concise due to the lack of "or reveal a hand without any" or some other dodge to cope with what happens if they don't have one.

There's several similar that say "and then discard a card" or "and then you choose a card from their hand", but not exactly this.

And then I realised it doesn't work because a creature might be a token or an animated land. Never mind :(

Reminiscent of Recoil.

Yeah, sadly even "nontoken creature" wouldn't help because of Stalking Stones or Ensouled Scimitar.

And Gideon Jura, and Mutavault and Genju of the Falls and Koth of the Hammer and Sculpting Steel and March of the Machines and Opalescence and Veiled Serpent and anything with manifest... I didn't try to list all the ways of turning other card types into creatures :)

In fact, I think almost every card type (artifact, land, enchantment, planeswalker) has a version that animates itself as a creature, except instant/sorcery. And almost every card type (land, enchantment, artifact) has a different spell that animates it as a creature, except instant/sorcery/planeswalker only get there with manifest.

I considered something like "discards that card or another creature card" which I think works in the rules (it's ok if "that is USUALLY what's described by "other" but not always), but didn't maintain the pleasing simplicity so it didn't seem worth it. In fact, they might very well have tried something similar with Recoil, before deciding there was no way to do it well and Recoil was good enough.