However, players can only select one mode
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
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
Brackets 4 and 5 are focused on a higher power or even a competitive experience
You might run a few extra Serpents in your Koma deck, but Koma builds its own army of tentacled terrors without assistance