This artifact depicts that concept perfectly, as you give your opponents the horse, and in exchange, you create a 1/1 token during each of your opponents upkeeps
It has great colors for interaction, so swap in what works best for you, and maybe that's more removal for potential blockers or more bounce spells
It only checks if a noncreature spell is cast, not whether it targets the prowess creature itself
This one is not a slam dunk like the next card on this list (and almost every one thereafter), but I do think that a deck that wants to make an Army might want it, especially out of the side
6 mana is a lot, but making all players creature spells cost 2 more is no small thing
Instant is great, one mana of fantastic and three damage is the icing on the cake