It became one of my more popular lists on Moxfield, with a few folks even asking for a Primer
Besides, you can play with such cards, and their end date will increase significantly
Sheoldred, the Apocalypse turns that around, so while you'll still lose life every upkeep, you'll gain much more back each time you use it to draw an ever-increasing number of cards
The Mirage rare is on the Reserved List which makes it an easy target for financial shenanigans, although there is a more important reason for the price increase: A few days ago Wizards announced a full Commander deck coming as a Secret Lair drop which happens to be a coin-flip deck with Okaun, Eye of Chaos and Zndrsplt, Eye of Wisdom as the face Commanders
This means that you'll reliably be able to continue to cast spells, regardless of how many cards are in your hand