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 .
Steps
1Declare Walker of Secret Ways as an attacker.
2When it isn't blocked, activate up to seven lands you control by tapping them, adding at least .
3Activate Great Whale's ninjutsu ability by paying and returning Walker of Secret Ways from the battlefield to your hand, putting Great Whale onto the battlefield from your hand tapped and attacking.
4When Great Whale enters the battlefield, it triggers, untapping up to seven lands.
5Activate Walker of Secret Ways's ninjutsu ability by paying and returning Great Whale from the battlefield to your hand, putting Walker of Secret Ways onto the battlefield from your hand tapped and attacking.
6Repeat from step 2.
7If you control up to seven lands that can tap to produce at least , this combo nets infinite mana.