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 (November 8, 2024—Magic: The Gathering Foundations)
- 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.”