So, for the above questions, I gave these answers: I want to spend as little as possible
Fetchlands excel most in Modern, Legacy and Vintage
Sheldon's Spellbook Keen Duelist I couldnt help but put the godfather of Commander into first place to honor his memory, and the Sheldons Spellbook Secret Lair is a beautiful tribute to Sheldon Menerys legacy
This is a really fun enchantment, and while its more of a shoe-in for decks that want vanilla creatures like Ruxa, Patient Professor, its honestly not the worst enchantment finisher for a deck full of evasive bodies like Merfolk, or Edric, Spymaster of Trest
Meanwhile, Izzet Charm can still counter that planeswalker (admittedly in a much less efficient way since it costs twice as much as Spell Pierce does), but it can also kill the Dark Confidant and, when the other modes are dead, potentially improve your hand by looting away some extra lands, Faithless Lootingstyle