When Lumra enters the battlefield, it triggers, causing you to mill four cards and then return all land cards from your graveyard to the battlefield tapped.
Repeat.
Results
Infinite blinking.
Infinite ETB.
Infinite landfall triggers.
Infinite LTB.
Infinite mana lands you control can produce.
Infinite self-mill.
Put all land cards from your library and graveyard onto the battlefield tapped.