Coral Atoll

Coral Atoll enters the battlefield tapped.
When Coral Atoll enters the battlefield, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.

This land enters tapped.
When this land enters, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.

Coral Atoll comes into play tapped. 
When Coral Atoll comes into play, return an untapped island you control to owner's hand or bury Coral Atoll.
ocT: Add {U} and one colorless mana to your mana pool.

Commander Legends

Commander 2014

Coral Atoll enters the battlefield tapped.\r
When Coral Atoll enters the battlefield, sacrifice it unless you return an untapped Island you control to its owner's hand.\r
{T}: Add {1}{U} to your mana pool.