There aren’t a whole lot of cards that get discarded that are extremely bad. Molten Reflection isn’t a huge deal with Arugals ability to get your more copies, and Leyline can discount them. The biggest problem would be Ruby Spellstone, but if that occurs too often then it may be worth adding in a Steamsurger / Ghastly Conjurer / Manabind + Arcanologist package.

They don’t have to be. I dropped the thalnos and the simulacrum to add in Leyline manipulator x2. It should give a bit more consistency to Book of Specters, and can help with the copies generated by Arugal