Source: Lost Kingdoms, pg(s). 60
No two inverted giants look the same, though all share some consistent features. Most have a gaping maw that cannot speak where a head should be, jagged bones serving as teeth. They are eyeless but possess an innate sense of direction, and sense prey through the despicable arcana in their beings. Their bodies are moist, splotched and marked with runes, and their flesh is translucent, rendering flesh and bones visible. The average inverted giant is over 20 feet tall and weighs 1,400 pounds.
The ritual for the creation of inverted giants was first taught to Runelord Alderpash by a nameless qlippoth, which he used to punish the giant Igramalash for a betrayal. The ritual was a unique success, and while he and other Runelords repeated the ritual with other giants, none resulted in a being quite as powerful as the first.
The creation of an inverted giant involves dark arcana that painfully and gruesomely turns its body inside-out while also keeping it alive and capable of thinking. The result is a horror as much a qlippoth as a giant that lives in maddening pain until death. Their gruesome and painful new forms serve as a punishment and reminder for their insolence, and few tried their masters' patience again.
During the lifetime of Thassilon, many runelords and their servants put their inverted giants in stasis so that centuries later they would continue to protect their masters' holdings. These inverted giants are often inadvertently released by explorers of Thassilonian ruins, their pain having long driven them to madness and hatred.