Phyrexian Metamorph

Clone has always carried a tax for printing on a permanent: pay the blue mana, take a copy of a creature, accept that the card is dead when there's nothing worth copying. The Phyrexian mana clause is what severs that dependency. By letting the blue pip be paid with two life, this Shapeshifter is castable in any deck regardless of color, which turns a parochial blue effect into colorless interaction. The other half of the rewrite is the copy clause: it copies artifacts as well as creatures, so it can become the best mana rock on the board, duplicate a game-warping equipment, or steal the rate of an opposing artifact bomb, and whatever it copies is now an artifact in addition to its other types. That last rider is doing real work, because it makes the copy vulnerable to artifact removal even when the original wasn't, and it feeds anything that counts or sacrifices artifacts. The Phyrexian mana mechanic was the era's most aggressive experiment in cost-flexibility, and most of its members were eventually banned out of competitive formats for being too cheap by half; this one survived because four mana for a Clone-on-an-artifact body is a fair rate, while the life option exists for the games where blue isn't available and a second copy of something is worth a chunk of your life total.