Hellbent

Hellbent is an ability word that indicates that a card is better if its controller has no cards in their hand.

Description
The mechanic was created by Aaron Forsythe.

Introduced in Dissension, it is found only on cards in that set aligned with the Cult of Rakdos guild (black and/or red). Hellbent was also used in Future Sight and Modern Horizons. Four cards printed after Future Sight have Hellbent-esque abilities, three of which involve drawing cards.

Hellbent can be many things, but the common thing is that it is active when the controller of the card with hellbent has no cards in their hand. It's written "Hellbent static ability, self-replacement, activated ability and/or triggered ability".

Rulings

 * If a hellbent ability of a spell or permanent is a static ability, the number of cards in its controller's hand is continually checked.
 * If a hellbent ability of a spell is a self-replacement that changes the effect of that spell, the number of cards in its controller's hand is checked as the spell resolves. It is not checked when the spell is cast.
 * If a hellbent ability of a permanent is an activated ability, the number of cards in the permanent's controller's hand is checked when that player tries to activate the ability. It is not checked when the ability resolves.
 * If a hellbent ability of a permanent is a triggered ability, the number of cards in the permanent's controller's hand is checked both when that ability would trigger and when that ability would resolve. If the player has one or more cards in their hand when the ability would trigger, it won't trigger. If the player has one or more cards in their hand when the ability would resolve, the ability does nothing.

Heckbent
An unnamed mechanic R&D likes to call "heckbent," is a riff off of hellbent. Heckbent cares about you having one or fewer cards in your hand (as opposed to hellbent, which requires your hand to be empty). If you do, your cards gain extra abilities that make either themselves or others better.

The ability is a black-red mini-theme in Amonkhet. It is more likely to return than Hellbent.

Vanguard
Lyzolda, the Blood Witch Avatar is a vanguard with 2 hellbent abilities.