#1 Cavern of Souls Cavern of Souls is not a new card to MTG
Its a little expensive for what it does, but its flexible in the decks it slots into, be it planeswalkers, +1/+1 counters, -1/-1 counters, and so on
If you danced with calamity a little too closely, and the total mana value of the exiled cards is greater than 13, the cards you exiled will remain there and you won't get to cast any of them
It's not all about being the best at drawing a bunch of cards all at once, just stick to your game plan and Green has your back.
It is another effect you want to combine with library shuffle else the ongoing value of the quality rapidly declines
While each of these are gems in their own right, the non-sequential Weeping Angels-themed Blink Saga is a personal favorite