I have an entity that extends EntitySmallFireball, and I override the onImpact method.

 

package realmoffera.entity.projectile;

import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.projectile.EntitySmallFireball;
import net.minecraft.util.MovingObjectPosition;
import net.minecraft.world.World;

public class EntityDreamFloaterShotRF extends EntitySmallFireball {
public static final int KB = 2;

public EntityDreamFloaterShotRF(World par1World) {
	super(par1World);
}

public EntityDreamFloaterShotRF(World par1World, EntityLivingBase par2EntityLivingBase, double par3, double par5, double par7) {
	super(par1World, par2EntityLivingBase, par3, par5, par7);
}

public EntityDreamFloaterShotRF(World par1World, double par2, double par4, double par6, double par8, double par10, double par12) {
	super(par1World, par2, par4, par6, par8, par10, par12);
}

@Override
protected void onImpact(MovingObjectPosition par1MovingObjectPosition) {
	if(par1MovingObjectPosition.entityHit != null) {
		System.err.println("Entity hit!");
		par1MovingObjectPosition.entityHit.motionX = motionX * KB;
		par1MovingObjectPosition.entityHit.motionY = motionY * KB;
		par1MovingObjectPosition.entityHit.motionZ = motionZ * KB;
		par1MovingObjectPosition.entityHit.posY += 10;
	}
	this.setDead();
}
}

 

For some reason, it prints the message, but doesn't do any of the motion or position changes.

Sometimes setting mothion doesn't work right.

 

Have you looked at the knockback code?

I've tried using the knockback method, nothing.