Restless Anchorage

This land enters tapped.
{T}: Add {W} or {U}.
{1}{W}{U}: Until end of turn, this land becomes a 2/3 white and blue Bird creature with flying. It's still a land.
Whenever this land attacks, create a Map token.

The Lost Caverns of Ixalan Promos

The Lost Caverns of Ixalan

Restless Anchorage enters the battlefield tapped.
{T}: Add {W} or {U}.
{1}{W}{U}: Until end of turn, Restless Anchorage becomes a 2/3 white and blue Bird creature with flying. It's still a land.
Whenever Restless Anchorage attacks, create a Map token.

If this becomes a creature because of an effect other than its own ability, its last ability will still trigger whenever it attacks.

If this becomes a creature but you haven't controlled it continuously since your most recent turn began, you won't be able to activate its mana ability or attack with it that turn.

Map tokens are a kind of predefined token. Each one is a colorless artifact with the artifact subtype Map and the ability "{1}, {T}, Sacrifice this artifact: Target creature you control explores. Activate only as a sorcery."