Unit function for affected units?

There is a new event to check when a unit's spell effect begins and a new condition so you can see what the spell is, but I looked and looked and couldn't find any way to make a trigger do something to units that were actually hit or affected by the spell, or things referring to the location the spell was cast on, only things for the caster of the spell. There are work arounds for spells with a single target and area spells like blizzard but for spells like forked lightning and chain lightning, where the targets are uncontrolled, is there anyway to make a trigger do something the units that are hit by the spell?

Maybe damaged units... but that would be very hard since in a batltle where u use spells units are wounded all the time... could maybe work in a small scale