In negative numbers , easy lets say soul drain or you suck the life from a unit bam , you have it come back to you , so set it negative , but make it get pulled down by gravity at the same time just time it right and bam you got a soul drain or suck life attack.
//set it to parabolic
//negative value
//get the arch just right
//make gravity do it's thing
//BAM AWESOME ATTACK that no one thought of =)