Deaths Shadow first started seeing play a few years ago in a very different type of deck in Modern, called Suicide Zoo
Midnight Reaper + Friends There are actually a ton of these little card advantage dudes, including Midnight Reaper, Liliana's Standard Bearer, Headless Rider, Archghoul of Thraben, and I could probably go on but Ive got some dead ones nipping at my heels
Electro is useful alongside any commander with firebending, but he's extra juicy with some commanders in particular
Mindsplice Apparatus can make all your spells insanely cheap to cast, but the quality of Standard instants and sorceries has diminished over the years
We sort of glossed over this news as WotC for some odd reason dumped ALL the big news all at once making it a bit difficult to absorb and process everything (think squirrel after a double-shot of espresso)
Each of them have made appearances in decks that have won in various formats and kitchen tables too