Juxtapose

A swap effect that pretends to be symmetrical and almost never is. The design rests on a hidden asymmetry: you cast it, so you choose when the snapshot is taken. You fire it when your opponent's biggest creature is a Baneslayer Angel and yours is a Wall of Omens, or when their Wurmcoil Engine is on the table and yours is a Sol Ring. The "greatest mana value" clause does the balancing work that distinguishes this from the Vedalken Shackles school of permanent theft: you cannot cherry-pick the target, which forces the deckbuilder to engineer board states where the trade is lopsided by construction rather than by selection. The artifact line, tacked on at the end of the text box, is the part that ages strangely; in 1994 it was a curiosity, since artifacts were mostly mana rocks and equipment did not exist, but in any environment with meaningful artifact creatures or vehicles it doubles the swing. Control-swap as a mechanic has mostly migrated to permanent theft (Treachery, Gilded Drake) or one-sided steals, because two-way exchanges are hard to cost and harder to balance. This is the early attempt at pricing the effect honestly: cheap, because the symmetry was assumed to do the balancing work, and the game has spent thirty years demonstrating that symmetry on a card you choose to cast is not symmetry at all.