The breath weapon of the arack dragon is a gaseous cloud, nearly transparent but faintly visible in daylight (but not under torchlight, moonlight or magical light short of a continual light spell). The size (area of effect) of the breath weapon, as mentioned above, is a direct function of the dragon's size. The height of the cloud is equal to the length of the dragon's body, and the radius it covers is equal to twice that number.
The breath weapon is usable only twice per day but does not dissipate quickly; the cloud normally persists for 10 turns. Living creatures (except for the arack) within the gas will notice a sticky dampness and a stifling lack of oxygen (described by the DM as "stuffiness"). This causes the loss of 1 additional hit point, cumulative, for each round that a victim is in the gas cloud: 1 point for the first round, +2 points in the second round (for a total of 3), +3 points in the third (total of 6), and so on.
If a victim retreats out of the cloud and remains out of its area of effect for a number of rounds equal to the time he or she was inside, then the cumulative effect is "reset" (to 1 point) if the cloud is reentered. If the "time out" is not as long as the last period of "time in," then the cumulative damage will continue to increase, counting upward from where the count left off, if the cloud and the victim again come into contact. A character who retreats out of the cloud and stays out long enough to "reset" the cumulative damage receives a saving throw (vs. poison), success indicating only half (of the total accumulated) damage was taken from the character's last time in the cloud.
The other effect of the arack's breath weapon is a damping effect that it has on magic. The gas reduces the combat effectiveness ("to hit" and damage figures) of all magical weapons by 2, and has an adverse effect on certain spells. A +1 or +2 weapon becomes, in effect, a +0 weapon, still magical in nature (with its other special properties intact) but having no enhanced combat usefulness at the moment. A +3 weapon becomes "worth" only +1, and so forth. Cantrips and first-level spells will fail automatically in the casting, or cease to operate - regardless of the level of the caster - if their area of effect coincides, in whole or in part, with the gas cloud. A character attempting to cast a spell of higher than first level must make a saving throw, using the proper row of the following chart, for the casting to succeed - but this save is only necessary if the spell is targeted into or through the breath cloud. (This is in addition to all other rolls that might be necessary to determine spell success or failure.)
If a magic item having charges is within the area of the breath, the DM may (optionally) secretly roll a saving throw for each charge remaining in the item, assuming in this case that the gas dissipates charges from the item upon exposure of the item to the gas, but does not prevent it the item from operating (except, possibly, by dissipating all of its charges). Artifacts and relics will not be affected in any case, their spells work normally within the gas, and they may not be discharged while in the gas.
Spell saving throws
Cantrips = Fail automatically
1st = Fail automatically
2nd = 20
3rd = 17
4th = 15
5th = 12
6th = 9
7th = 5
8th = 1
9th = Succeed automatically
Rings = 7
Rods = 15
Staves = 14
Wands = 16