Description[]
"Break the jar before a battle to unleash a killing storm"
The official description is slightly misleading: a jar can be used during the Skirmish Phase of a Battle (unlike the "use in battle" treasures, which are used in the Planning Phase). It will kill or injure a percentage of the enemy army (around 15%) regardless of their total number and disrupt any action they were trying to take that round. It is therefore very effective against large forces such as Vestantes raiding parties. You may use multiple jars in the same battle.
Acquisition[]
Several Whirlwind Jars are acquired upon successfully completing the Orlanth and Ernalda ritual. Their exact number is random and may depend on how successful the ritual was.
Other Stories[]
A Whirlwind Jar is also a treasure in King of Dragon Pass, see here.