Self-contained, visually appealing packaging, and immediately playable
Phyrexian Fleshgorger can be cast early for a smaller version with its prototype ability, or if you draw it later you can cast it for its full glorious size
Exploration is a one mana enchantment that allows you to play two lands per turn instead of one
Even if it's not a special summon from an extra There are some strong monsters, so it's not unconditionally weak I can't say Of course sin and Works well with Earthbound Immortal, etc
There are a lot of Doctors with fun effects, but they really don't fit the theme
For example, Hostile Negotiations works great in a narrow section of discard decks, but Sheoldred, the Apocalypse can go in pretty much any black Brawl deck you build