No creature without flying will be able to block that turn, including creatures that lose flying after Seismic Stomp resolves and creatures without flying that enter the battlefield after Seismic Stomp resolves.
Legalitet:
Standard: Ej legal
Pioneer: Legal
Modern: Legal
Legacy: Legal
Vintage: Legal
EDH / Commander: Legal
Pauper: Legal
Explorer: Ej legal
Historic: Ej legal
Brawl: Ej legal
Premodern: Ej legal
93/94: Ej legal