Calamities

Calamities are what happen when a mage goes past their Unlimited Mana Threshold. "Calamities take effect immediately, but their nature may not always be apparent to the wizard (see the table for details). Calamities don’t normally cause the spell to fail. However, if the Calamity Check total is 29+, then the spell does fail unless the caster can make a Will roll at a penalty equal to the bonus to the Calamity Check."GURPS Thaumatology, p.77
The Pyramid #9 Unlimited Mana article has the original Calamity Table.
==Reference==
Category:Rules