CROP ROTATION Not many instants make it on to these lists, but Crop Rotation cleanly takes a spot, because in order to play it, you need a land in play, which youre basically always going to have
Sporoloth Ancient and Sporesower ThallidIndividually are kind of slow but not threats so they sneak under the radar
Xenagos on the other hand, costs 1 mana more, but needs 7 devotion to become a creature
The nuance of it dealing damage upon becoming tapped (as opposed to just being used) is a powerful teacher
This lets any creature come down swinging with double power right away, which could very easily be a 24-power Ghalta, Primal Hunger, or worse
The 2-mana artifacts are at their absolute best in mono-colored decks, where their cost reduction applies to nearly all cards in the deck