Restless Vents

This land enters tapped.
{T}: Add {B} or {R}.
{1}{B}{R}: Until end of turn, this land becomes a 2/3 black and red Insect creature with menace. It's still a land.
Whenever this land attacks, you may discard a card. If you do, draw a card.

The Lost Caverns of Ixalan Promos

The Lost Caverns of Ixalan

Restless Vents enters the battlefield tapped.
{T}: Add {B} or {R}.
{1}{B}{R}: Until end of turn, Restless Vents becomes a 2/3 black and red Insect creature with menace. It's still a land.
Whenever Restless Vents attacks, you may discard a card. If you do, draw a card.

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.