GigaBash

Click Story and select Woolley, then 2. Into the Jungle. Any difficulty works including Casual.

There will be two fights between you and Skorak. The quickest way to defeat him is on Casual. Hold down X for your Heavy Attack, aim, and let go to ram him. Rinse and repeat until death.

Once the second fight starts, you will notice he is not wearing his shell anymore. Work his health down to a small amount but do not completly kill him this time. Move near his shell and start holding Y to use your Ultimate Attack (sucks in) on Skorak. Woolley will spit him out in a snowball form. Put distance between Skorak and his shell... quickly pick his shell up (B) and aim like a mortor using the red arch. His shell can either hit him in the air or on ground for the achievement to unlock. Skorak must however, die.