"Halt, traveler. Whatever you seek, you will not find it here."

The Lost Caverns of Ixalan

Sentinel of the Nameless City

Vigilance
Whenever Sentinel of the Nameless City enters the battlefield or attacks, create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery.")

Vigilance
Whenever this creature enters or attacks, create a Map token. (It's an artifact with "{1}, {T}, Sacrifice this token: Target creature you control explores. Activate only as a sorcery.")

Vigilance
Whenever Sentinel of the Nameless City enters the battlefield or attacks, create a Map token.