Is there any event that can harm the player and can be shot with considerably high speed? I tried using enemies and rocks as projectiles with the use of belts, but no matter how high I set the speed, they always move slowly. All I need is to make them travel horizontally, preferably Tube Turtle since it looks fine in mid-air and is affected by gravity under all circumstances.

Place a TNT at a certain distance from an enemy with a lot of hit points (Tuf Turtles are a good victim) so that it harms, but not kills them, and the explosion will give them a considerable boost.

When you put a tube turtle on a belt, the speed of the belt will be set by the event parameters of the tile above the belt, not of the belt itself.

Woah, it really works. The effect is awesome.