Help from a complex spell

[RazeHunter]

I created a spell that shoots a astroid(from inferno). However I want this spell to make an extra effect if it hits a certain target. Example, Jade(my Hero) uses catalyst missile(the Inferno) in an area with enemies and they get damage, but when she does it again but hits a unit that is speific like Tiberium or Gas(from abomination) the CM(Catalyst Missile) upon impact and hits these targets not only just damage them within the aoe but creates a huge explosion to these specific targets. Its like my goal is to make the CM just a astroid that damages enemy when hitted but when a specific target is in range to the impact they explosde viotly(doesnt kill them tho, but nearby the explosion damages entities except the gas or tiberium cause theyre invulnerable anyway). In conclusion: Inferno shoots = Normal, But it shoots and a specific target included within it = Big Explosion.