Each time they attempt to cast a spell, after the casting dice have been rolled a Night Goblin Shaman may eat a Magic Mushroom. This adds D6 to the casting result. This dice does not count as a power dice, and cannot contribute to Unlimited Power. However, if you roll a 1 on this dice you must roll a further D6. On a roll of 4+ nothing else happens, but on a roll of 1-3 the Shaman suffers a wound with no armour saves allowed, and the spell automatically fails.