Delirium

Delirium is an ability word introduced in Shadows over Innistrad block 
==Description==
Delirium is a tweak on threshold. It highlights cards that get better if you have four or more card types represented in your graveyard. In a typical game, a player will have creatures and instants in the graveyard, and all decks have lands. This is functionally three of the four types, which means players will need to dedicate deck space to one of the other five types, as well a way to get lands in the graveyard. There are many different kinds of delirium abilities, including activated abilities. <c>Winter, Cynical Opportunist</c> is unique in how it checks for delirium while exiling graveyard cards, compared to the static or triggered checks of others.
The card types that could show up in your graveyard are artifact, creature, enchantment, instant, land, planeswalker, sorcery, battle and kindred. Supertypes like basic or legendary, and subtypes like Vampire or Equipment don't count. The number of cards doesn't matter, as long as you have four or more card types. 
===History===
In Shadows over Innistrad block, Delirium was in all colors, but primary in green and secondary in white and black. Discard outlets because of madness and permanent sacrifice were the primary ways of fueling Delirium.
During its reuse in Modern Horizons 2, it was shifted to being the blue and red archetype. The higher number of artifacts and odd-typed landcyclers supported getting types into the graveyard, alongside a pair of instant and sorceries split cards in blue and red, and red enchantment creatures as well.
It also made appearances in Double Masters, Thunder Junction Commander, and Modern Horizons 3.
In Duskmourn: House of Horror, it is one of the main mechanics again. This time, enchantments are the focus type that all colors have, while manifest dread gives players two ways of getting odd types into the graveyard.
A delirium-adjacent effect, best known for being on <c>Tarmogoyf</c>, scales for every type in the graveyard. <c>Omnivorous Flytrap</c> uniquely looks for "super-delirium", granting an additional bonus for six types.
==Rulings==
*The card types in Magic include artifact, battle, creature, enchantment, instant, kindred, land, planeswalker, and sorcery. Legendary, basic, and snow are supertypes, not card types; Horror and Room are subtypes, not card types.
*A single card can contribute multiple card types for the purposes of delirium. For example, if your graveyard contained Attack-in-the-Box (artifact creature) along with Shardmage's Rescue (enchantment) and Jump Scare (instant), you would have four card types among cards in your graveyard, and your delirium abilities would be enabled.
*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.
*Some instants and sorceries with delirium abilities have an upgraded effect when they resolve or a modified cost as they're cast if there are four or more card types among cards in your graveyard. They check that number only while they're resolving or cast respectively and don't count themselves, since they aren't in your graveyard yet.
*Some delirium abilities are activated abilities of permanents. To activate such an ability, there must be four or more card types among cards in your graveyard. The number of card types is not rechecked as the ability resolves.
*Some (but not all) triggered delirium abilities use an intervening "if" clause. There must be four or more card types among cards in your graveyard in order for these abilities to trigger; otherwise, they won't trigger at all. There's no way to have the ability trigger if there aren't enough card types, even if you intend to raise that number in response to the triggered ability. *The number of card types is checked again as the trigger resolves; if that number has become too low, the ability does nothing. If the card types in your graveyard change but the quantity of card types stays the same (or increases), then the delirium triggered ability will still resolve.
*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.
==Examples==
==References==