Caster is an obsolete term that used to refer to the player who cast a spell. In general, cards that were printed with the term "caster" have received errata in the Oracle card reference to say "controller"
From the glossary of the Comprehensive Rules (April 12, 2024—Outlaws of Thunder Junction)
- Caster (Obsolete)
- An obsolete term that referred to the player who cast a spell. In general, cards that were printed with the term “caster” have received errata in the Oracle card reference to say “controller.”