How do I change a unit?

Another question arose. How do I add a "projectile" animation (or effect) to a unit? Here are two specific examples: first, the recently added centaurs, which replaced the Inferno Horses, but they don't have arrows or any other projectile animation when they attack (it's just instant damage to the target). Second, the Destroyers (formerly Temptresses); their new feature is that, despite having minimal damage, they attack all enemy units and machines at once in ranged combat, but again, there's no "projectile" animation. I was thinking of using a Lightning animation for this (like the one used by the Zealot and the Titans' skill).

I would be grateful for any help :(

Added 4 minutes later
[Edited] The Destroyers use the Cast Biara animation, which is compatible with their model, for their ranged attack.