This card was printed in the following sets:

Card Name: Symbol Set Block
Thassa, God of the Sea Theros (Mythic Rare) Theros Theros
Thassa, God of the Sea Secret Lair Drop (Mythic Rare) Secret Lair Drop

This card has restrictions in the following formats:

Format Legality
Pioneer Legal
Modern Legal
Legacy Legal
Vintage Legal
Commander Legal
x For more information regarding each format and play style modifications, visit the Banned / Restricted Lists for DCI-Sanctioned Tournaments page on the Magic: The Gathering website.

Gatherer works better in the Companion app!