Blood Baron is also completely absurd against any deck that pretty much cant touch him, such as Aristocrat decks or B/G Midrange
While they read like niche color hate, the absurd efficiency of a one-mana counterspell/one-mana removal split card elevates this to an S+ sideboard card for red decks, and a mirror-beater for any blue deck capable of fetching Volcanic Island which is all of them
The Replenish deck could sit back, lose card advantage turn after turn with Attunement, and still come out and win at its leisure as Parallax Wave, Opalescence, Seal of Cleansing, and other enchantments all entered play at the same time
4 - Clockwork Percussionist This card definitely turned some heads during Duskmourn spoiler season because it is most assuredly a great card for Burn
You need a fair few of the latter as well as a heavy commitment to white before you can look at this for your list