Lumra, Bellow of the Woods + Port of Karfell + Spelunking + Thaumatog
Lumra, Bellow of the Woods
Port of Karfell
Spelunking
Thaumatog
Infinite death triggersInfinite creature ETBInfinite landfall triggersInfinite creature LTBInfinitely large creature until end of turnInfinite mana lands you control can produceInfinite creature sacrifice triggersInfinite self-millPut all land cards from your library and graveyard onto the battlefieldInfinite card drawInfinite draw triggers
How it works
Activate any number of other lands you control by tapping them, adding at least 3.
Activate Thaumatog's first ability by sacrificing a land other than Port of Karfell, giving Thaumatog +1/+1 until end of turn.
Repeat step 2 until you control no other lands except Port of Karfell.
Activate Port of Karfell's second ability by paying 3, tapping and sacrificing it, causing you to mill four cards and return Lumra from your graveyard to the battlefield tapped.
Lumra enters the battlefield and dies as a state-based action due to having 0 toughness.
Lumra's enter-the-battlefield ability triggers, causing you to mill four cards and return all land cards from your graveyard to the battlefield untapped due to Spelunking.