This card was printed in the following sets:

Card Name: Symbol Set Block
Walking Ballista Aether Revolt (Rare) Aether Revolt Kaladesh
Walking Ballista Secret Lair Drop (Rare) Secret Lair Drop
Walking Ballista Double Masters (Rare) Double Masters

This card has restrictions in the following formats:

Format Legality
Pioneer Banned
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!