How to blast units off

Ok, I have made a spell which is named Big Bang but I am just wondering, how do you make the units look as though they have been blasted off from the centre of the explosion? As in make them fly away. The only flying thing I've tried is impale, (They make them fly up in the air but I want to make them fly off backwards and impale has that ugly thing sticking from the ground) any suggestions?

P.S.: If you want to see the spell, go http://www.wc3campaigns.com/forums/s...threadid=42115 and download the map. The spell is on a hero named Blood Elf Lord on the light forces. It is the ultimate spell.