A Wicker man was a large wicker statue reportedly used by the ancient Druids (priests of Celtic paganism) for sacrifice by burning it in effigy.
In Game
When Commodus was captured the Britons sold him to the monitor tribe. Due to Commodus being an off spring of Nero, the monitor tribe were going to sacrifice him to the burning pagan. However Vitallion's defiant and bravery of proving the monitors' were men caused him to be placed in the wicker man instead of Commodus.
Marius Titus arrived just before the burning began, but Glott wanting to intimidate the Roman started the burning. After Glott's death Marius had his men destroy the Wicker man saving Vitallion and several of his men.