Satoru Umezawa and Prosperous Thief on the battlefield.
Prosperous Thief does not have summoning sickness and cannot be blocked by an opponent.
You control up to seven lands that can tap to produce at least ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) ({B} magic symbol) .
Steps
Declare Prosperous Thief as an attacker.
When it isn't blocked, activate up to seven lands you control by tapping them, adding at least ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) ({B} magic symbol) .
Activate Palinchron's ninjutsu ability by paying ({2} magic symbol) ({U} magic symbol) ({B} magic symbol) and returning Prosperous Thief from the battlefield to your hand, putting Palinchron onto the battlefield from your hand tapped and attacking.
When Palinchron enters the battlefield, it triggers, untapping up to seven lands.
Activate Prosperous Thief's ninjutsu ability by paying ({1} magic symbol) ({U} magic symbol) and returning Palinchron from the battlefield to your hand, putting Prosperous Thief onto the battlefield from your hand tapped and attacking.
Repeat from step 2.
If you control up to seven lands that can tap to produce at least ({4} magic symbol) ({U} magic symbol) ({U} magic symbol) ({B} magic symbol) , this combo nets infinite mana.