[17] Cards like Wurmcoil Engine really shine in environments where players are casting a ton of creatures
Targeting a creature with an ability was trivial, and with Springheart Nantuko backing Nadu up, you had a constant source of new creatures to target with abilities that cost zero mana to essentially draw your entire library
Sephiroth, the Savior is an excellent fit for the Phyrexian angel, and Tetsuya Nomura's art here is gorgeous
or they sit around the battlefield, close to lands, unattached to any card in particular, but affecting the game in some way for you
these were specific effects that made one archetype exceptionally good within that color identity
No cards after 1999's Urza's Destiny are on the Reserved List, and "never" will be