Cheapest priced copy (The List): $0.59 at Card Kingdom, near mint, their price list as of .
Darksteel Garrison 
Artifact — Fortification · Rare · Future Sight · #167
Fortified land has indestructible.
Whenever fortified land becomes tapped, target creature gets +1/+1 until end of turn.
Fortify {3} ({3}: Attach to target land you control. Fortify only as a sorcery. This card enters unattached and stays on the battlefield if the land leaves.)
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.59 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Future Sight | 167 | Rare | $0.69 | $7.99 |
| The List | FUT-167 | Rare | $0.59 | — |
4 rulings from Wizards of the Coast
- 1 May 2007The triggered ability is mandatory. If you don’t have a creature to target, you must target another player’s creature, if possible.
- 1 May 2007The second ability triggers whenever the fortified land becomes tapped, not just when it’s tapped for mana.
- 1 May 2007Fortification is to lands what Equipment is to creatures. Except for the difference regarding what kind of permanent it can affect, Fortifications and Equipment follow the same rules.
- 1 May 2007If Darksteel Garrison and the fortified land would be destroyed at the same time, only Darksteel Garrison is destroyed.