2 Part Technique - Despite the tremendous disadvantage of having your opponent on the verge of passing your half guard, you are not completely left without recourse. Regain an underhook on the side of your half by switching figure-four to the inside, where then you can twist your hips and bridge open enough space to pummel for it. Before he has a chance counter your new-found underhook to adjust his pass accordingly, escape your hips to the outside and insert a butterfly hook. If you've let him pass his knee through your half guard, resort to the Frame Escape to gain your needed underhook and push his leg back deeper into your half. Once you've circled your instep in front of his thigh, throw him onto his back with the Hook Sweep from Half Guard. Depending on where he positions his arm; facilitate the sweep and take away his post by either pushing his arm into his body, or pulling it away.