Penny decks

What is the Penny Dreadful format in Magic?

Penny Dreadful is an unofficial Magic Online Constructed format built around extremely inexpensive cards. Its legal card pool is determined by Magic Online prices and is updated periodically, allowing cards from throughout Magic's history to become legal when their online price falls low enough.

The result is a rotating budget format whose card pool can change for reasons completely unrelated to set rotation. Powerful cards can enter or leave simply because the Magic Online market moves.