Lands you control excluding Port of Karfell can tap to produce at least ({3} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Archelos is untapped.
Steps
Activate any number of other lands you control by tapping them, adding at least ({3} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Activate Coastal Hornclaw by sacrificing a land other than Port of Karfell.
Repeat step 2 until you control no other lands except Port of Karfell.
Activate Port of Karfell's second ability by paying ({3} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) , 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.
Repeat.
Results
Infinite death triggers.
Infinite ETB.
Infinite landfall triggers.
Infinite LTB.
Infinite mana lands you control can produce.
Infinite sacrifice triggers.
Infinite self-mill.
Put all land cards from your library and graveyard onto the battlefield.