Mud Ball

Every throw that reaches the ground leaves a Mud Block behind, and that is the real character of the thing. Damage is close to incidental. Used on purpose it is a way to drop mud into a pit or across a gap you would rather not stand next to, which is handy when you want jungle grass to take hold somewhere awkward.

Throw a stack of these across an arena and you will be digging the arena out again afterwards. The old Sandgun trick applies: torches, platforms and sloped blocks on the floor give the projectile nowhere to place anything, so it just deals its damage and disappears. Do that before the fight, not after.

Snowballs cover the same idea and leave nothing behind, and the mud version throws noticeably quicker in the hand. The catch is that nothing on your character improves it. Ranged bonuses do not apply, so a kitted out gunner gets more out of real ammunition and should treat these as a utility item instead.