He found a secluded room with a mysterious locked lorebook, which he unwittingly opened by playing a few musical notes
I use metallic purple sleeves for this purpose - theyre easily distinguishable from actual cards, unlike black or white sleeves that you may already have due to potentially clashing with the Magic card border color
The set will be releasing on June 13th, which means previews will likely begin in full around May 20th
Also regarding interacting with what comes from the Exile, we use several cards that bring support to it - Nalfeshnee and Mizzix, Replica Rider to copy our spells, The Lost and the Damned to create more tokens, Passionate Archaeologist and Keeper of Secrets to deal damage to our opponents directly, and, to indeed make these spells happen from the Exile, we have Etali, Primal Storm and Plargg and Nassari