Spawn of Chaos are moved in the Compulsory Movement part of the Chaos player's
Movement phase, moving 2D6" each turn. The player has no control over the distance moved, but must nominate in which direction the Spawn will move before rolling the dice (this must be in a straight line).

If the Spawn's movement is sufficient to take it into an enemy unit then it counts as charging, following all of the normal rules. The target may make a charge response as normal, counting the Movement value rolled as the Spawn's maximum charge distance (for the purposes of fleeing, standing and shooting, etc).