His first order of business as Magister was to convince the government of Tashalar that all wizards required legal protection and proper standing within the community. The idea of peace, and the prosperity that that would bring, appealed to Tashalar's government, but they did not care for potentially taking orders from mages.
The rulers of Tashalar decided to hire mages from Mulhorand to eliminate Onsilur the "Ruling Magister" and rid them of their headache. Onsilur successfully defended himself against these strike-and-flee duels until Ansel Burwyth was able to trap his soul within a kiira. Thrilled with his success, and lured by the promise of riches stashed within Onsilur's Liongirt Tower, Ansel immediately hid the kiira and raided Onsilur's home. He was quickly destroyed by the tower's many defensive wards.
The fate of both Onsilur and Ansel remained a mystery for several years before the rulers of Tashalar finally returned to their ways and Liongirt Tower was plundered of its wealth, but not before dozens of hopeful wizards perished in the attempt.
As of 1367 DR, Ansel's hiding place for the kiira had yet to be discovered. Onsilur eventually went insane trapped within the gem. Even the name of the elves who might claim ownership of it were forgotten with the fall of Myth Drannor. Some sages believed that the kiira was taken somewhere within the Dragonreach.