Card not found was a major player in Standard for a while and has made appearances in pretty much all Constructed formats, including some play in Vintage
An alt-art Leader of a fan-favorite character or a top competitive choice can command high prices (often significantly higher than the regular Leader card)
Since Kenrith still costs a little over a dollar, he definitely makes up for one awesome budget MtG Commander
Necropotence was seen as a great defining feature of black, but unfortunately proved to be too strong and carried with it too much rules baggage. Yawgmoths Bargain was Mark Rosewaters attempt to make a new Necropotence that addressed both of these issues
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Not Legal Toolbox Notes and Rules Information for Sheoldred, the Apocalypse: If you and an opponent draw a card at the same time, you choose the order that the triggered abilities will resolve in
With the power of righteousness they keep evil at bay