Play Glacial Chasm either from your hand or from your graveyard.
When Glacial Chasm enters the battlefield, its second ability triggers, causing you to sacrifice another land you control.
Play any land from your graveyard.
At the beginning of your next upkeep, Glacial Chasm's cumulative upkeep ability triggers, allowing you to choose not to pay the cost and sacrifice it instead.
Repeat.

Prevent all damage that would be dealt to you

Glacial Chasm

Thalia and The Gitrog Monster

Ramunap Excavator

Whenever a creature enters the battlefield under an opponent's control, it enters tapped due to Thalia and the Gitrog Monster.
Holding priority, activate Royal Assassin by tapping it, destroying the creature.
When the creature dies, Royal Assassin triggers, untapping Royal Assassin.
Repeat.

Combos with "Thalia and The Gitrog Monster"