It comes up constantly at card shows, in grading discussions, and whenever someone pulls a card and immediately tilts it sideways to check the borders
Let's run down the list: 4 colorless mana gets you protection from everything until your next turn as long as you cast it, and then starts a clock that, at the increasing cost of your life, draws you cards
Edgar Markov is by far the best Vampire to lead your armies, having an eminence ability that lets you pump out Vampire tokens even while hes in the Command Zone, an ability which is arguably too powerful
There have been plenty of other hosts throughout the various Spider-Man timelines, but serial killer Kletus is their most recognizable combination
Add in some sales of individual drops, and let's estimate that there might be somewhere around 50,000 of each individual Secret Lair God in existence