(The expected value of your low roll is the dice size minus the high roll EV plus 1, so 1.875 in the case of two d4s.) For the d8s used on Arcane Endeavor, the expected value of your high roll is 5.8125, which means that if you prioritize drawing cards, youll be drawing about six cards on average, and getting to cast a spell of about mana value 3
Shiko and Narset, Unified leads the deck, showing off the new flurry mechanic from the main set
Creatures that come under your control later in the turn won't be copies of the chosen creature
(Collector viewpoint) From a collector point of view, the answer is: yes, they can be very worth it, as long as you understand what you are buying
Larger playing card sizes can be great when creating educational flash cards or novelty cards