A soul bag (often referred to as a shard bag) is a bag used by Warlocks to hold more Soul Shards than they would normally be able to carry in conventional containers. The soul bag consumes a regular container slot, however, so it reduces the number of available slots for non-Soul Shard items. The value of the trade-off is up to the individual Warlock. Soul Shards harvested by the Warlock are automatically stored in an equipped soul bag when acquired, making tedious Soul Shard housekeeping a thing of the past.