Orcus sometimes infuses a ghoul with a stronger dose of abyssal energy, making a ghast. Whereas ghouls are little more than savage beasts, a ghast is cunning and can inspire a pack of ghouls to follow its commands. Instinct: Insatiable hunger for human flesh

• Paralyze with it's claws
• Call Ghouls to it's aid

ike maggots or carrion beetles, ghouls thrive in places rank with decay and death. A ghoul haunts a place where it can gorge on dead flesh and decomposing organs. When it can’t feed on the dead, it pursues living creatures and attempts to make corpses of them. Though they gain no nourishment from the corpses they devour, ghouls are driven by an unending hunger that compels them to consume. A ghoul’s undead flesh never rots, and this monster can persist in a crypt or tomb for untold ages without feeding. Instinct: insatiable hunger for human flesh

• Paralyze non-elf with it's touch
• Call more ghouls

Violent and territorial, quaggoths climb the chasms of the Underdark. They maul their foes in a frenzy, becoming even more murderous in the face of death. Instinct: Eat and kill

• Maul foes in a frenzy when wounded
• Eat something

Astute combatants, quadrones serve as artillery and field officers in the regiments of modron armies. Instinct: Serve Law and Order

• Disintigrate when killed/destroyed
• Spontaneously Advance to Next Form

From somewhere in the darkness, a gurgling moan is heard. A form lurches into view, dragging one foot as it raises bloated arms and broken hands. The zombie advances, driven to kill anyone too slow to escape its grasp. Instinct: Do their creator’s bidding without fear or hesitation

• Paralyze with an eye ray
• Weaken and Damage with an eye ray
• Terrify with an eye ray

The ballistae can't perceive (and thus they ignore) creatures that keep to the easternmost 60-foot section of the hallway. Once they detect intruders, however, the ballistae amble forward on hinged legs to close the distance. If a ballista has nothing to attack on its turn, it returns to its starting position. Instinct: Protect the area

• Shoot a bolt of fire

Privileged drow males who lack the strength and fighting prowess to train as warriors have no recourse but to pursue the study of magic. For them, it is a matter of survival. Female drow with a natural affinity for the arcane arts may also become drow mages, although they are much less common. Instinct: Seek Political Gain

• Summon an Imp/Quasit or Shadow Demon
• Summon magical darkness
• Cast Magic Missile (2d4 damage)
• Block an Attack with a Shield Spell
• Cast Fireball (2d6 ignores armor)
• Cast Cloudkill
• Levitate!

The bulk of the yugoloth population is made up of mezzoloths, which are human-sized insect creatures covered in dense chitinous plates. Mezzoloths serve as foot soldiers in yugoloth armies, their wide-set eyes glowing red as the mezzoloths bear down on their foes. Violence and reward are the fundamental drives of a mezzoloth, and powerful beings that promise one or the other can easily attract them into service. Although it has lethal claws on its four arms, a mezzoloth typically wields a trident in two of them. If surrounded by enemies, a mezzoloth exhales toxic fumes that can choke and kill whole groups of creatures. Instinct: Violence and reward

• Teleport to anywhere it can see
• If surrounded exhales toxic fumes that can choke and kill (extra d6 damage when damaged)
• Use magic to darken the area
• End a magical effect

A revenant forms from the soul of a mortal who met a cruel and undeserving fate. It claws its way back into the world to seek revenge against the one who wronged it. The revenant reclaims its mortal body and superficially resembles a zombie. However, instead of lifeless eyes, a revenant’s eyes burn with resolve and flare in the presence of its adversary. If the revenant’s original body was destroyed or is otherwise unavailable, the spirit of the revenant enters another humanoid corpse. Regardless of the body the revenant uses as a vessel, its adversary always recognizes the revenant for what it truly is. Instinct: Exact vengence before it's year is up

• track those it seeks revenge against
• Paralyze it's sworn enemy with a glare
• regenerate wounds not caused by fire

A nothic is a monstrous creature with terrible talons and a single great eye. When driven to violence, it uses its horrific gaze to rot the flesh from its enemies’ bones. Rather than gaining the godlike supremacy they crave, some wizards who devote their lives to unearthing arcane secrets are reduced to creeping, tormented monsters by a dark curse left behind by Vecna, a powerful lich who, in some worlds, has transcended his undead existence to become a god of secrets. Nothics retain no awareness of their former selves, skulking amid the shadows and haunting places rich in magical knowledge, drawn by memories and impulses they can’t quite understand. Instinct: Reverse its condition

• Rot living flesh with its gaze
• Gaze at someone and learn one fact or secret about them