Gym Leader Challenge is a popular example and is one of many listed in the Alternative Play Handbook linked below
Wargamer has everything you could need, from a guide to MTG Cascade to the Commander damage rules
Secret missions appear in the missions tab after they've been completed and are ready to be redeemed for rewards, but until then there's no way of knowing that they're there until that point (unless you're using the guide above, of course)
Aurelia is also an ideal candidate for a high-powered draft environment, so she seemed like a shoe-in for this set
Then Burning of Xinye deals 4 damage to each creature
, , Sacrifice this land: Return target Bat, Lizard, Rat, or Squirrel card from your graveyard to your hand