Tawnos's Tinkering

In Commander, Tawnos's Tinkering earns a slot in any spell-slinging deck that wants flexible, cheap redundancy for its best instants and sorceries — storm builds, Kalamax piles, and Zada engines all want this effect. Pauper is where it genuinely overperforms: one mana for a copy of a cantrip, removal spell, or burn shot is among the most efficient plays available at common. In Legacy and Vintage the competition from Twincast and Fork is real, but the cost difference is negligible and the common printing makes Tawnos's Tinkering trivially accessible. Modern and Pioneer have enough redundancy in the copy-spell space that it slots in without displacing anything critical. Across every format it's legal in, the card does exactly one thing and does it cheaply enough that the question is never whether to include it — it's whether you need the effect at all.