If we can get The Book of Vile Darkness, Eye of Vecna, and Hand of Vecna on the battlefield at the same time, we can exile them all to make an 8/8 indestructible Zombie God named Vecna, which makes Zombies, draws us cards, and gets absolutely huge in combat
And his ability Disguise grants him Evasiveness during your turn
Commander Masters Precon Spoilers - All Four Face Commanders Revealed
It only asks that you play creatures on curve in order to keep evolving
Why it makes the blood token is probably the discard it can provide, but Im sure it will be a fine addition to Strefan, Maurer Progenitor and Anje, Maid of Dishonor decks everywhere as well
However, the downside to Pokmon ex cards is that, if defeated, they enable the opponent to the player who summoned them to draw two prize cards, instead of the usual one