Thalia's ability affects each spell that's not a creature spell, including your own.
2018-03-16
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
Legalitet:
Standard: Legal
Pioneer: Legal
Modern: Legal
Legacy: Legal
Vintage: Legal
EDH / Commander: Legal
Pauper: Ej legal
Explorer: Legal
Historic: Legal
Brawl: Legal
Premodern: Ej legal
93/94: Ej legal
Thalia, Guardian of Thraben är Legal i dessa block: Innistrad