Mindwrack Demon — ruling 1

Mindwrack 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.

Mindwrack Demon — ruling 2

The 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.

Mindwrack Demon — ruling 3

The 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.

Mindwrack Demon — ruling 4

Because 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.

Mindwrack Demon — ruling 5

In 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.

Mindwrack Demon : règles, fonctionnement et interactions (MTG)

Mindwrack Demon is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

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.

How it works : Mindwrack Demon

Original English text — Wizards of the Coast / Scryfall

#1April 8, 2016· Wizards of the Coast
Mindwrack 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.
No other card is named in this ruling.
#2April 8, 2016· Wizards of the Coast
The 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.
No other card is named in this ruling.
#3April 8, 2016· Wizards of the Coast
The 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.
No other card is named in this ruling.
#4April 8, 2016· Wizards of the Coast
Because 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.
No other card is named in this ruling.
#5April 8, 2016· Wizards of the Coast
In 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.
No other card is named in this ruling.