Cheapest priced copy (Duel Decks: Blessed vs. Cursed): $0.99 at Card Kingdom, foil, near mint, their price list as of .
Mindwrack Demon 
Creature — Demon · 4/5 · Mythic · Shadows over Innistrad · #124
Flying, trample
When this creature enters, mill four cards.
Delirium — At the beginning of your upkeep, you lose 4 life unless there are four or more card types among cards in your graveyard.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
3 printings · $0.99 to $2.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Blessed vs. Cursed | 41 | Mythic | — | $0.99 |
| Shadows over Innistrad Promos | 124s | Mythic | — | $2.79 |
| Shadows over Innistrad | 124 | Mythic | $0.99 | $0.99 |
5 rulings from Wizards of the Coast
- 8 April 2016Mindwrack Demon's delirium triggered ability does not include an intervening "if" clause. This ability triggers at the beginning of your upkeep regardless of the number of types in your graveyard, and it checks that number as it resolves to determine whether you lose 4 life or not.
- 8 April 2016Because you consider only the characteristics of a double-faced card's front face while it's not on the battlefield, the types of its back face won't be counted for delirium.
- 8 April 2016The card types in Magic are artifact, battle, creature, enchantment, instant, kindred, land, planeswalker, and sorcery. Supertypes (such as legendary and basic) and subtypes (such as Human and Equipment) are not counted.
- 8 April 2016In some rare cases, you can have a token or a copy of a spell in your graveyard at the moment that an object's delirium ability counts the card types among cards in your graveyard, before that token or copy ceases to exist. Because tokens and copies of spells are not cards, even if they are copies of cards, their types will never be counted.
- 8 April 2016The number of card types matters, not the number of cards. For example, Wicker Witch (an artifact creature) along with Catalog (an instant) and Chaplain's Blessing (a sorcery) will enable delirium.