Obelisk of Armageddon

Fortified land has "{w}{w}, {t}, Sacrifice this land: Tap all lands target player controls."
Fortify {w}{w} ({w}{w}: Attach to target land you control. Fortify only as a sorcery.)
The obelisks are our greatest defense against any unholy threat. They drain the land of its mana
to stop our enemy's advance.