Delirium

Delirium is an ability word introduced in Shadows over Innistrad block   and reused in Modern Horizons 2 as a color-pair archetype.

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. There are many different kinds of delirium abilities, including activated abilities.

The card types that could show up in your graveyard are artifact, creature, enchantment, instant, land, planeswalker, sorcery, and tribal. 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.

In Shadows over Innistrad block, delirium was in all colors, but primary in green and secondary in white and black. During its reuse in Modern Horizons 2, it was shifted to blue and red.