• To be precise, they apply ((listed damage+2)/3), rounded down, to the squares they affect every 1280 ticks. Since a combat round (aka: turn) is 7500 ticks, a cloud can usually apply very slightly less than 6 times per turn. A cloud will trigger four times per point of Lingering listed on the spell, so each point of Lingering can also be thought of as making the cloud last on field for 68% of a round.

Further Information:

• Because clouds add 2 to the listed damage before dividing and rounding down, a spell with a listed damage of 1 will deal 1 damage instead of 0, a spell with listed damage of 4 will deal 2 instead of 1, so on and so forth.

• Additional effects not part of the initial spell (aka: nextspells) are applied on a spell landing/being cast, lingering clouds will NOT reapply the nextspell every time they apply damage. Notably, this does effect Sulphur Haze and Freezing Mist: they only apply their additional fatigue damage on the initial cast.

• Lingering effects can be cast on and stack in the same square. Each cloud will trigger independently.

• A cloud "remembers" who cast it, so spells like Damage Reversal, blessings like Blood Vengeance, and items like The Protection of Geryon will work correctly against Lingering effects.

• Three spells in the base game; Smokeless Flame, Magma Eruption, and Splash of Molten Metal (that's the name of the extraeffect of Liquid Flames of Rhuax), have an attribute that is displayed as "Adds lingering heat where it hits (<value> AN fatigue)". This attribute functions differently than normal clouds and lingering effects: it creates a cloud that lasts only two pulses, but deals the full listed amount of damage as AN heat fatigue damage.

• Lingering will inherently always have a minimum of AoE 1, even when modded to be single target through the use of AoE 0.

• A modded cloud spell with "#effect 109" for capped damage will not have its damage reduced to 1/3. It will still only deal a maximum of 1 final damage due to being capped damage, however.

• Cloud spells that use a "Hard MR Check", as opposed to a regular "MR Check" or a "Easy MR Check", do not work. The effect of such a spell will be applied with no check possible. There are no Lingering spells in the base game (aka: vanilla) that use a Hard MR Check.

• To mod a spell to have Lingering, add 1000(multiplied by the value of Lingering you want) to its #effect. For instance, to make a Lingering 6 damage spell you would have "#effect 6002", 2 for the damage effect and 6000 for Lingering 6. The Dominions 5 Modding Manual does not mention this.