As soon as you cast it, you gain protection from everything for a turn, allowing you to have a little breathing room while your opponent is prevented from doing any damage to you
4 Mana Crypt Like it or not, despite the cards absurd financial price tag, Mana Crypt is one of the best ways you can ramp in the Commander format
Five of these cards are Mystical Archives, and three are regular non-foils
While this isnt a formal rule, the concept behind summoning sickness is
The fact that this is a repeatable tutor effect obviously makes this artifact amazing
This lets the deck deal explosive amounts of damage, since most of them have prowess, and can tactically bounce permanents (or destroy them with burn damage) to deal the most damage possible in just one combat phase