Battle, Siege, and War spell durations for Ars Magica

There was an interesting idea shared on Atlas Games Ars Magica forums a long time ago for spell duration based upon battles and wars. Credit to Dunia for the idea. It reminded me of many of the durations used in both online games and other pen and paper RPGs. For a wizard who concentrated their skills in war such as many Tremere, Tytalus, or Flambeau this might be very appealing.

When I first read the post I thought that having Battle duration as equivalent to D:Sun was a bit on the expensive side as very few battles last this long; and in writing these versions of the new durations I have added conditions to their scope. Battle, Siege, and War are slightly different from how they were proposed in the forums.

As time has passed I’ve rethought and now think that there is a way to allow casual use of this style of duration which is a little more expensive, and also allow a dedicated war magus to use them with a bonus.


The difference comes down to the player buying a virtue, making a breakthrough for the effects, or just using them casually.

Hermetic Virtue – Warfare Magic (Minor +1) The magus has been trained in special disciplines especially devoted to warfare, and has access to three new durations: Battle, Siege, and War.

With a minor breakthrough or a special minor virtue (Warfare Magic) I’d allow the following three durations as:

Duration: Battle (equivalent to D: Conc)

The spell lasts as long as its target is engaged in combat (tracking actions by counting combat rounds), and ends automatically if they sleep.

If cast with a Target affecting multiple individuals, the spell’s duration is tracked separately for each participant, and ends on a particular target if they leave the battle.

The intent of the Battle duration is to allow effects to last roughly at least as long as Diameter without also unbalancing the value of the Sun duration. An example effect would be Gift of the Bear’s Fortitude altered to battle so that it allows preparation, and lasts only as long as needed, and may also avoid potential warping if used prudently.

Duration: Siege (+2, equivalent to D: Sun)

A Siege spell inherits all the properties of the Battle duration, lasts for the length of a siege, and also must be cast on multiple targets.

A siege activity may be any prolonged event where two groups are locked in armed conflict, often in standoff. A manor house may be besieged just like a castle.

Duration: War (+3, equivalent to D: Moon, and always a Ritual)

The spell must be cast on a group of at least 100 individuals and lasts as long as its targets remains engaged in a War. What exactly constitutes a War is up to the troupe, but typically a war must be declared formally in some manner, and any peace, truce or treaty for longer than a day ends the spell.

A War spell may optionally be cast in advance, and is considered latent and does not take effect until the next battle the character fights in, and then expires at the end of that battle; the latent magic expires automatically at Moon Duration if the character has not fought in a battle before then. The effects of warping begin when the spell is cast, not when it is triggered.

Note that without a breakthrough or the virtue each of these durations could be used as part of a non-standard formulaic spell by increasing the cost my one magnitude (ie. Battle becomes +2, Siege +3, and War +4).

2 thoughts on “Battle, Siege, and War spell durations for Ars Magica

  1. You’ve written “The magus has been trained in special disciplines especially devoted to warfare, and has access to three new ranges: Battle, Siege, and War.”

    You mean three new durations, not three new ranges

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