21 cards where the set is “stx” and the cards are cards that are included in the standard contents of draft boosters and the text includes “learn”

Guiding Voice (Strixhaven: School of Mages #19)
Professor of Symbology (Strixhaven: School of Mages #24)
Sparring Regimen (Strixhaven: School of Mages #29)
Study Break (Strixhaven: School of Mages #34)
Arcane Subtraction (Strixhaven: School of Mages #36)
Divide by Zero (Strixhaven: School of Mages #41)
Dream Strix (Strixhaven: School of Mages #42)
Pop Quiz (Strixhaven: School of Mages #49)
Eyetwitch (Strixhaven: School of Mages #70)
Hunt for Specimens (Strixhaven: School of Mages #73)
Poet's Quill (Strixhaven: School of Mages #82)
Academic Dispute (Strixhaven: School of Mages #91)
Enthusiastic Study (Strixhaven: School of Mages #99)
First Day of Class (Strixhaven: School of Mages #102)
Igneous Inspiration (Strixhaven: School of Mages #107)
Retriever Phoenix (Strixhaven: School of Mages #113)
Field Trip (Strixhaven: School of Mages #131)
Gnarled Professor (Strixhaven: School of Mages #133)
Overgrown Arch (Strixhaven: School of Mages #139)
Cram Session (Strixhaven: School of Mages #170)
Rise of Extus (Strixhaven: School of Mages #226)

The message was clear to Sorin—time to search for something else.