Pretty much for a thing I want to do.
Alright, first thing first. A Ballista

It moves slowly, can hold two players and shoots spear projectiles with a reload time of three seconds. The longer you hold down click, the farther the spear goes.
Next thing, a mounted crossbow.

Cannot move, can only be aimed vertically and fires arrow projectiles with a reload of half a second. It basically acts like a powerful but hard-to-aim bow that's immobile.
Lastly, default horse with a lance. Pretty much acts like the normal horse only when you click, you speed forward and if possible, you damage anything you touch.
And that's pretty much it.