Now that I have GRoY, one mythical basis for killing Umatum seems spot on. Section 6 of Heaven Corrupted has Shargash being "stuck directly by Umatum and thrusts the invader onward and follows. Umatum is fatally wounded and wobbles inside of Umatum's path, protecting the City. They fight with missiles and eventually Umatum wavers, then crashes down in the far north."
At least it is a basis. Another is the death of the Andam horde in Entekosiad.
Jeff
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