Well said Black...
I actualy did a little tinkering and made it drop smoke grenades...
I used the GDI Bomber Projectile base, changed the explosion damage to 0, added a particle system for smoke effect, frame rate and changed to make the smoke linger...
I thought it would look cool, but it didnt do much so i added a +1 damage like when people breath in smoke

, meh, it works for me ^^