Satoru Umezawa and Walker of Secret Ways on the battlefield.
Walker of Secret Ways 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 Walker of Secret Ways 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 Walker of Secret Ways 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 Walker of Secret Ways's ninjutsu ability by paying ({1} magic symbol) ({U} magic symbol) and returning Palinchron from the battlefield to your hand, putting Walker of Secret Ways 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.