Thousand-Faced Shadow + Great Whale + Skullsnatcher

Prerequisites

Skullsnatcher and Great Whale do not have summoning sickness. An opponent cannot block Skullsnatcher or Great Whale. You control up to seven lands that can tap to produce at least {2}{U}{U}{B}.

Steps

1. Declare Great Whale and Skullsnatcher as attackers.
2. When they aren't blocked, activate up to seven lands you control by tapping them, adding at least {2}{U}{U}{B}.
3. Activate Thousand-Faced Shadow's ninjutsu ability by paying {2}{U}{U} and returning Skullsnatcher from the battlefield to your hand, putting Thousand-Faced Shadow onto the battlefield from your hand tapped and attacking.
4. When Thousand-Faced Shadow enters the battlefield, it triggers, creating a token copy of Great Whale that is tapped and attacking.
5. When the Great Whale token enters the battlefield, it triggers, untapping up to seven lands.
6. Activate Skullsnatcher's ninjutsu ability by paying {B} and returning Thousand-Faced Shadow from the battlefield to your hand, putting Skullsnatcher onto the battlefield from your hand tapped and attacking.
7. Repeat from step 2.
8. Deal combat damage using the Great Whale tokens, dealing infinite combat damage to the defending opponent.
9. If you control up to seven lands that can tap to produce at least {3}{U}{U}{B}, this combo nets infinite mana.