Also shown off were two upcoming legendary creatures, which can be used to head up players Commander decks in the popular format
He is also fairly broad unlike a lot of the more interesting cards for deck design and so while he is not a must have for a cube he is a good way to make things more complex and interesting
You cant play four copies of a card in the main deck and two more in the sideboard, as that would be utterly broken
Ive been killed before by someones Dualcaster Mage on my Torment of Hailfire, and getting the best part of Dualcaster on a spell that can also copy your triggers and do a redirect
Tucking something on ETB is incredibly strong, especially in the blink colors of blue and white, and doing it to each opponent is going to be at least passably good in EDH
Diluvian Primordial does the latter for each opponent, which makes it a huge threat once it resolves