Killstreak had expected the giantess to fall forward, and in a sense, she did. Her upper body, however, had decided to halt it´s momentum, and shift towards him instead of it´s original course. An interesting move, that much was certain. The giantess´ own legs was hindering any kind of surprise momentum she might have hoped to spring on Killstreak in such a way. Not that it mattered much. He was really fucking fast, after all. As it was, he was pretty certain he could have strolled out of the way of her incoming upper body even without his speed hack. Attacking him with her back turned like that also struck him as a confounding move. He could do just about anything he wanted, and she would be completely unable to see it. Especially considering her limited peripheal vision due to the helmet.
But his speed hack did remain. So he pulled out a snack bar and ate it slowly while he surveyed the area with his binoculars. He could see Arthur Greystoke still fighting the group of scrubs. How they were not yet dead was astounding. Greystoke must be having one of those days.
Throwing away the empty snack bar paper, and withdrawing his binoculars, he turned his attention back to the giantess, who´s upped body had at this point just started to getting affected by the downwards pull of gravity at about 73 degrees. Her legs wobbled awkwardly to the side, he couldn´t imagine her finding it a graceful maneuver. Ah well. He started walking backwards and to the side, trying to figure out where her head would land. Having placed himself about a meter next to the spot of impact, he retrieved a bomb from his inventory, wielding a revolver in his left hand, and the bomb in his right. "Don´t blow before you´re inside." He said to it.
KRACK! Her head hit the ground, and it would be at this point that Killstreak took a step closer, flipped his revolver, and hit her at the side of her helmet with the blunt end of it at such blinding speed, the impact force would peak at roughly 10 tons force. Killstreak didn´t put too much into it, as he simultaneously threw the bomb into the opening of the giantess´ cuirass, around the neck. Likely jamming it in between her armor and her chest. The following explosion would be amplified by the pressure generated by the nearly impenetrable enclosed space. With nowhere to go but back out, the force would focus itself into her chest, and upwards, "uppercutting" her in the face.
The pistol whip into the side of the helmet, conveniently at ear height, would, in addition to the force of the impact itself, vibrate the metal helmet and generate a greatly amplified sound inwards that would, if not shatter her eardrums completely, leave her in terrible pain and discomfort. This, in addition to the burning leg, and the bomb in the cuirass, would surely make her wish she had never crossed paths with Killstreak Von Leetus.
But she did.
Immediately after tossing the bomb, which was roughly 0,3 seconds after the giantess´ head hit the ground, Killstreak moonwalked 10 meters away, at 200mph, before stopping. That should place him at a safe distance of the imminent explosion, which would occur the moment the bomb flew into the cuirass.