'Now.'
After monitoring the battle for a while, Lucas attacked at the very first opportunity he had when the Jaburian had just dodged an attack from the desolate ape, leaving behind an opening.
*Boom*
The vestige released a loud noise, but by the time the sound had reverberated, the projectile was already before its target. It was too late for the Jaburian to dodge, and it only barely managed to flinch its body before the projectile —an energy bullet— penetrated right through its flesh and gouged out a large wound.
The wound was so large that it almost severed the Jaburian into two. Its body was barely intact as it lay on the floor, inhaling and exhaling heavily through each motion.
After the first shot, Lucas didn't stop and reloaded right away, this time aiming for the desolate ape.
The latter was stunned by both the noise and the attack, and barely responded in time for the next shot.
*Boom*