The six-sided die directly introduces RNG into the game, which if introduced today, would probably cause much more concern in the player base Double Spells Each color has a common instant or sorcery with a mana value of five across the board thats considered a double spell. They each do something when they're cast as well as at the start of the next game, a nice 4th wall-breaking mechanic that can lead one player to having a much worse time next game
Coming down on turn 3 or 4 and immediately draining for 3 stabilizes your board, but unlike Rhino, it can't block without help
In fact, it might be a good idea to just change Magic: The Gathering to Bottle Gnomes: The Gathering
With the latter, you can play a simple card draw instant like ponder to give flash to whatever type didn't have it prior
Senseis Divining Top can also draw a card and put itself back on top to save it from removal
In Standard, Aftermath Analyst decks are losing the New Capenna lands is Iridescent Vinelasher good enough to make those decks viable in Pioneer