Some monsters have special abilities beyond mêlée attacks and basic offensive spells. Caution may have to be taken if you come across monsters with such abilities:
Rather than attack you directly, some monsters prefer to simply mug you of your hard-earned gold. The amount they steal is dependent on how much gold you are currently carrying, but you can reclaim stolen gold if you kill the monster in question.
Be wary of the Harpy, for when she steals gold, she steals the lot! Another mention should go to the Thief that appears in the Nightmist training arenas, because arena monsters' gold drops are only 25% of what they are in the field - this means that if they steal gold from you, you will only get back 25% of what you lost.
If a monster (or a Ranger) hypnotises you, your chance of landing a successful hit is reduced by 10%. At first this is not something to be worried about, although if the monster perseveres, you could find your whole party becoming very unreliable.
This is the only monster ability that has a positive effect on players... healing them. Normally this spell is in the domain of the NPC Priests that are found within churches and chapels, although the Seasonal Painting is a rare example of a boss that casts this alongside a couple of harmful elemental spells.
Like a Mage's Invisibility spell, renders the monster invisible until it attacks again or is revealed with a Vision spell. Some monsters have a genuine magical spell for this purpose, while others simply conceal themselves in the scenery.
This is an automatic ability that sometimes triggers whenever it attacks or casts a spell upon a player. When a player becomes poisoned, they will receive damage every 30 seconds until it wears off or is cleared with a potion or the Cleanse spell.
The strength of the poison depends on the monster - most poisons only hurt you for 1 damage, which is an annoyance more than anything as it can cause a Cleric to waste their heal spell on you, although some poisons hurt you for much more than this, in which case it becomes an abject priority to administer an antidote.
Some monsters are able to regenerate their health periodically, usually about 10% of their total health every 30 seconds, although this is not always the case (e.g. Resca). This forces players to use large, strong parties and effectively prohibits strategic fallback, for the monster may have regenerated to full health by the time you return.
This is a special variant of summoning, where a monster effectively duplicates itself. To date, only the Dust Devil and the Fire Ant Soldier do this, and this can make an extremely dangerous fight, as it gets harder the longer you take due to the damage received and the difficulty of killing them all off before they replicate again.
Some bosses, and a handful of regular monsters, periodically call for reinforcements. How this occurs depends on the entity, and usually comes in the form of a lackey entering the room or being generated in some way to join the fight, although a few monsters physically grow extra appendages (e.g. the Hydra Body) or self-replicate (see above).