Hoomhoffers are large arachnidoids used as heavy cavalry, close air support or shock troops by Baron Klaus Wulfenbach and later Martellus von Blitzengaard. Each "hoom" (as they are sometimes called) is ridden by a mahout who directs its actions. Normally hoomhoffers
They are constructs reportedly made from enlarged dust mites (so they would be big enough to study), with air pumps installed on their backs that allow an arachnid of that size to breathe. The pumps are an inconvenience, but the hoomhoffer's incredible toughness, strength, newly acquired ability to fly, and fearsome appearance more than make up for this.