Darksteel Garrison

Fortification is the artifact subtype that never got a second act: a keyword built to do for lands what Equipment did for creatures, shipped once as a proof of concept and then quietly shelved. This is the lone card carrying the entire mechanic, which makes its design choices the whole argument for whether lands were ever worth bolting toys onto. The answer it offers is defensive first and offensive second. Granting a land indestructible matters against a Wildfire or an Armageddon, but lands are exactly the permanents most board wipes already ignore, so the protection lands somewhere odd: it shields the type of permanent that was already hardest to sweep. The combat rider is the more curious half, keying off the land becoming tapped rather than off any deliberate action, which means it fires the moment you spend that mana for anything at all: a single-creature pump stapled to your normal sequencing, repeatable on every turn you tap the fortified land. The re-attach cost, restricted to sorcery speed, is the friction that keeps one Garrison from skating across a board of lands at will. As a piece of design history it is the road not taken, a fully realized keyword that never received the supporting cast a real mechanic needs. What survives is one card doing the work of an entire subtype, which is either a collector's footnote or a puzzle box, depending on how much you enjoy building around things no one else bothered to.