Bloodghast

Bloodghast can't block.
Bloodghast has haste as long as an opponent has 10 or less life.
Landfall — Whenever a land you control enters, you may return Bloodghast from your graveyard to the battlefield.

Summoning it is easy. Controlling it is another matter.

Aetherdrift

The Lost Caverns of Ixalan Commander

Bloodghast can't block.
Bloodghast has haste as long as an opponent has 10 or less life.
Landfall — Whenever a land enters the battlefield under your control, you may return Bloodghast from your graveyard to the battlefield.

Bloodghast's landfall ability triggers only if it's already in your graveyard at the time a land enters under your control.

The landfall ability triggers whenever a land enters under your control for any reason. It triggers whenever you play a land, as well as whenever a spell or ability (such as Rampant Growth) causes you to put a land onto the battlefield under your control. It will even trigger when a spell or ability causes another player to put a land onto the battlefield under your control (as can happen with Yavimaya Dryad's ability, for example).

When a land enters under your control, each landfall ability of the permanents you control will trigger. You can put them on the stack in any order. The last ability you put on the stack will be the first one that resolves.