He creates a magical simulacrum (clone) of himself and plays on Tristan's knowledge of him back in Carthak, where he was a "book-bound idiot." He explains to Daine that people who are Black robe mages study books and learn nothing practical.
The character replicates a magical copy of himself and uses Tristan's understanding of his past self in Carthak, where he was perceived as intellectually limited. He explains to Daine that Black Robe mages prioritize studying books over acquiring practical knowledge.