The Magic: The Gathering card Blex, Vexing Pest has seen a 525% price spike, jumping from $1.20 to $7.50 in the past couple of weeks. It's a heart-warming tribute to a character cut down in their prime, and offscreen too - to add insult to injury.
Of course, the real reason demand for this card has gone up is that Blex's descendant, Blech, Loafing Pest, is an exciting new MTG commander who works with all the same creature types as Blex: pests, bats, snakes, insects, and spiders.
Unless you want to focus on just one critter type (building Blech as insect tribal seems quite popular) you're probably going to want Blex in your deck, since it's the only card that will act as a lord for all of your creatures. Blex provides life gain when he dies, which can also trigger Blech's board-wide buff. Plus, it's just a good old-fashioned flavor win (or a heart-warming reunion?) to have them both in the same deck.
Despite a range of useful abilities on the creature half, one of Blex's best attributes is that it's a double-faced card, with an impressive card draw spell on the back. Search for Blex can get you up to five cards from the top of your library (really solid for Golgari!) at the not-insignificant price of four mana and 15 life.
Not every deck can stomach something like that, but if you're playing Blech, Loafing Pest then you're incentivized to go for a lifegain strategy. It's therefore far more likely that you'll have spare life to use as a resource, or can draw into lifegain cards to help offset the cost.
Providing a board-wide buff, and powerful card advantage, it's no surprise that Blex is jumping up in value. Extended art versions of the card are selling for between $14 - 20, and foils are up to about $10.