Volo, Guide to Monsters | Mercurial Pretender | Great Whale

Cards

You control up to seven lands that can tap to produce at least ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) .
You have no other Shapeshifters on the battlefield or in your graveyard.

Activate up to seven lands by tapping them, adding at least ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) .
Cast
Mercurial Pretender by paying ({4} magic symbol) ({U} magic symbol) .
Volo triggers, creating a token copy of
Mercurial Pretender.
The token
Mercurial Pretender enters the battlefield as a copy of
Great Whale, untapping up to seven lands.
Activate up to seven lands by tapping them, adding at least ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) .
The nontoken
Mercurial Pretender enters the battlefield as a copy of
Great Whale, untapping up to seven lands.
Activate the nontoken
Mercurial Pretender by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) , returning it from the battlefield to your hand.
Repeat.