Troop System Rendering Help in my TD Game

Hello fellow devs! I am creating a td game and I have picked up on client sided rendering, So for my troop system the server will make the troop attack and damage the troop and the client is supposed to render the bullet.For this I tried using fastCast, But i havent figured out how to make the client know the server fired a ray.

I also want some help to see if I am making the troop system efficiently

Module Script:

function attacks.towerAttack(tower)
	while tower.Parent == workspace.Towers.Spawned do
		task.wait(tower:GetAttribute("Cooldown"))
		local target = bestTarget(tower)
		if target then
			tower:GetAttribute("Target", target)
			-- workspace.Towers.Spawned[tower.TowerHash].PrimaryPart.CFrame = CFrame.new(tower.CFrame.Position, Vector3.new(workspace.Enemies.Active[target.EnemyHash].PrimaryPart.Position.X ,tower.CFrame.Position.Y, workspace.Enemies.Active[target.EnemyHash].PrimaryPart.Position.Z))
			
			local enemies = game.ReplicatedStorage:WaitForChild("Events").getEnemies:Invoke()

			if enemies[target.EnemyHash] == nil then continue end
			
			local direction = (enemies[target.EnemyHash]["CFrame"].Position - tower.Position).Unit
						
			cast:Fire(tower.Position + Vector3.new(0, 3, 0), direction, 150, behaviour)
			
			enemies[target.EnemyHash]["Health"] -= tower:GetAttribute("Damage")
			
			if enemies[target.EnemyHash]["Health"] <= 0 then
				enemies[target.EnemyHash]["Dead"] = true 
			end			
			
			local result = game.ReplicatedStorage:WaitForChild("Events").getEnemies:Invoke(enemies)
			
			--tower.TotalDamage += tower:GetAttribute("Damage")
		end	
	end	
	
	return 
end

The server script:

placingEvent.OnServerEvent:Connect(function(plr, tower, placer, name, hash)
	
	local off = replicated.Towers:FindFirstChild(name)

	plr.Cash.Value -= off.Price.Value
	local part = Instance.new("Part")
	part.Name = name
	part.Parent = workspace.Towers.Spawned
	part.BrickColor = BrickColor.new("Really red")
	part.Size = Vector3.new(1,0,1)
	part.CFrame = tower
	
	part:SetAttribute("Damage", towerdb[name].Damage)
	part:SetAttribute("Cooldown", towerdb[name].Cooldown)
	part:SetAttribute("Range", towerdb[name].Range)
	part:SetAttribute("CFrame", part.CFrame)
	part:SetAttribute("Mode", "First")
	part:SetAttribute("Target", " ")
	part:SetAttribute("TowerHash", hash)
	
	placingEvent:FireAllClients(placer, part, name)
	
	attacks.towerAttack(part)
end)

I tried using length changed but it isnt firing for some reason, Any help?

just use a sync it with the server like i did in mine. I made a few tutorials if you wanna check them out.

Can u give me an example, Also is my script good for optimization? Give me all the tips you have

like the server will send a message to the client to spawn an enemy, and the enemy would move based on delta time, so it basically cant really be super unsynced. Get a receive rate of 1kb/s with lots of enemies (1000+)

I use the same system with 150kb/s for 500 enemies, Probably because the enemies are highly detailed. So can you link me your channel because that sounds awesome!

Oh nevermind I heard you from YT before. But people made fun of me for copying your tutorials so i made my own system