Init (1d20+3=19)
Roscoe runs to the Kobold with a wicked grin that says "Say goodnight lizard"
Reckless attack (1d20+4, 1d20+4, 1d6+3=[6, 4], [20, 4], [2, 3])
Adding Critical damage (1d6+3=5) - Critical hit 24, damage 7.
EDIT: if the Kobold was slain by Fulgrim's firebolt Roscoe will attemp to...