The Lost Caverns of Ixalan Commander

Regal Behemoth

Trample
When Regal Behemoth enters the battlefield, you become the monarch.
Whenever you tap a land for mana while you're the monarch, add an additional one mana of any color.

Trample
When Regal Behemoth enters, you become the monarch.
Whenever you tap a land for mana while you're the monarch, add an additional one mana of any color.

Commander Masters

Conspiracy: Take the Crown

Trample
When Regal Behemoth enters the battlefield, you become the monarch.
Whenever you tap a land for mana while you're the monarch, add one mana of any color to your mana pool (in addition to the mana the land produces).