As Carl's laughing burrowed its way into Gilgamesh's mind, he scrambled to think of some way, any way to turn that absolute disregard into despair. If he killed Carl before that, then the boy's laughter would haunt him forever and that simply couldn't happen, he knew no matter what he did after would be temporary at best.
To him, when Carl told him to enjoy the victory, he was wrong,
To Gilgamesh, victory was absolute and unquestionable, it meant your enemy was broken and dead.
Whilst Carl had simply been trying to trick him into draining enough divinity for his body to recover from the strain of containing it, he had pulled an old trick out of his sleeve and won without even meaning to.
"Hey, "Giggly-Grumbles". Have fun facing Margo after this, you just ruined his game."
