Worms Armageddon | Lethal Cluster Bomb
This trick is easy and efficient, yet it depends on the position of your oponnent's worm. Once you can lift him using any kind of jump, you can go a little below his level, select Cluster Bomb, aim to the ground and drop it. Usually you should be able to cause a damage of 90+ HP.
Good luck & have fun!
Soustruh - http://wormscesky.cz