It was not a decision that they came to lightly. The absence of thaums in the world would mean the absence of magic. Alphai’s various societies had become dependent upon magic in everyday life. There was no need to light a torch if you could cast a light spell. Tenser’s Floating Disc was more efficient than any oxcart, and the various cure wounds, remove disease, and raise dead spells cast meant that what we now consider common first-aid was, well, non-existant.
But it was decided that the alternative was undesirable. While the elves beat ferociously at the Hub’s gates, the high mages of Hyldor began a ritual that would gather up all the thaums from all reaches of Alphai, and send them…away.
You may be wondering how, when all magic was unreliable, that such an important spell could be cast with any chance of success. Ritual magic relies on a consensus of will, an agreement of reality, if you will. The will of one mage is small compared to the will of many, and if many mages impose their will upon the thaums they wish to charge, there is a greater chance that the charge will hold and not mutate. Ritual magic was the only way any reliable magic could be performed during the time of the Surge. If you needed a mending spell cast during that time, it would require a ritual with no less than five participants. The spell the high thaumaturgists cast, the exodum evocarum, required over a hundred participants, and the great wizards employed the abilities of anyone who could cast even a simple spell to impose their will upon the thaums.
The ritual worked. Many mages died during the casting, giving up their life-force to fuel the spell when their mental will proved inefficient to contain and control the energies they were using, but the end result was success. The air in the great Theurgic Chamber was rent open, leaving a tear in the very fabric of reality. At once, all the thaums in Alphai, from the reaches of the Phirdic Tundra to the deserts of Mazi’nil, from the dragons to the elves to the sorcerers, from the precious metal Orchalcum, all magical potential was ripped from them and rushed into the rift, like water down a drain. A great storm appeared over the mage’s tower, and the storm lasted for a while day while the thaums surged and parted.
Then, the storm subsided, and disappeared. The rift in reality closed in upon itself, and the former mages, the greatest thinkers of their time, were left unable to cast any magic.
The Surge had ended as a result of the mages' Purge, and the people of Alphai began to pick up the pieces.
The Elves, however, had their own problems to deal with.