Caster was pondering how to destroy the sun. That way, she could remove today's light, and get to kill the man. But, Gilgamesh threw a tantrum, which kind of worked out. Heroic Spirits couldn't really be killed, so if she caused a ruckus now, then she could end this Grail wars before it began, and force the Grail to sustain another twenty five years of Gilgamesh's quite childish demands. Which, from the looks of it, probably wouldn't happen.
"A true king does not command by force alone. He requires the will to see through all obsticales, the support and admaration of his subjects, and the wisdom to know when to apply force, and when to apply a more tactful approuch. Any less, is merely a tyrant. So, maybe that is your true title, Tyrant of Tyrants?" Caster put in, loud enough to be heard clearly over all the rabble-rousing.