Hub Ruins

Whenever a land you control taps for mana, put a keystone counter on Hub Ruins.

Remove a keystone counter from Hub Ruins: Hub Ruins becomes a copy of target land until end of turn.

Remove ten keystone counters from Hub Ruins: Search your library for a legendary land and put it on the battlefield, then shuffle.

If a source were to remove Hub Ruins from the game, instead choose a land you control and shuffle it into your library.