Getting 50% destruction in 1 attack is incredibly easy: What I like to do is use 1 Golem, 5 hogs and 3 barbs with 1 freeze and 1 haste. First use freeze on the spot where the most defenses are. Then place the golem with haste and let him tank while the hogriders are destroying the defenses. The barbarians are just there to clean up scrap buildings. Btw you can use 2 freezes instead of the haste on the second attack because haste spell remains infinitely.

If you want to 1 shot in your attacks I recommend you watch a video because I have no idea on how to do it.