Innistrad: Midnight Hunt was chock-full of Cube goodies, and Innistrad: Crimson Vow looks like a fitting follow-up
When you are reliably finding one and winning with it when you just have three then you don't overly need a 4th
Because of the way Rex, Cyber-Hound's second and third abilities are worded, he can continue to use abilities of exiled cards even after leaving play
A common or two snuck on to this list, but most of those will be in the next two categories
Jeska, Thrice Reborn will let you triple Bruse Tarl's combat damage each turn
Kenrith, the Returned King A little bit of everything, all of the time Are you someone who likes abilities on creatures you can activate at any time, and also someone who likes five-colour decks