Satoru Umezawa and Skullsnatcher on the battlefield.
Skullsnatcher does not have summoning sickness and cannot be blocked by an opponent.
You control up to five lands that can tap to produce at least ({2} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Steps
Declare Skullsnatcher as an attacker.
When it isn't blocked, activate up to five lands you control by tapping them, adding at least ({2} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) .
Activate Peregrine Drake's ninjutsu ability by paying ({2} magic symbol) ({U} magic symbol) ({B} magic symbol) and returning Skullsnatcher from the battlefield to your hand, putting Peregrine Drake onto the battlefield from your hand tapped and attacking.
When Peregrine Drake enters the battlefield, it triggers, untapping up to five lands.
Activate Skullsnatcher's ninjutsu ability by paying ({B} magic symbol) and returning Peregrine Drake from the battlefield to your hand, putting Skullsnatcher onto the battlefield from your hand tapped and attacking.
Repeat from step 2.
If you control up to five lands that can tap to produce at least ({3} magic symbol) ({U} magic symbol) ({B} magic symbol) ({B} magic symbol) , this combo nets infinite mana.