How To Charge With FilteringEnabled?

When you click MouseButton1, fire a Remote Event/Function. You could either pass it with an argument to see if they are holding down or let go (true or false). On InputEnded, fire either the same Remote (with false or whatever you set as parameter) or a different one. Then you can use a NumberValue as an iterator for growing it, then handle it on the server.

https://developer.roblox.com/en-us/api-reference/class/UserInputService

Also, please provide some code or proof that you tried next time.

Tool.Activated:Connect(function()StartCharging:FireServer()end)
Tool.Deactivated:Connect(function()DoAbility:FireServer()end)

So far I've got this

LocalScript

local UserInputService = game:GetService("UserInputService")

local Held = false

UserInputService.InputBegan:Connect(function(inputObject)
    if inputObject.UserInputType == Enum.UserInputType.MouseButton1 then
        Held = true
        game.ReplicatedStorage["Magic"]["Charging"]:FireServer(true)
    end
end)

UserInputService.InputEnded:Connect(function(inputObject)
    if inputObject.UserInputType == Enum.UserInputType.MouseButton1 then
        Held = false
        game.ReplicatedStorage["Magic"]["Charging"]:FireServer(false)
    end
end)

ServerScript

game.ReplicatedStorage["Magic"]["Charging"].OnServerEvent:Connect(function(player, Held)

    while wait(.1) do
        if Held == true then
            print("held")
        end
    end

end)

My only problem is it keeps firing when I release the key, it doesn't seem to be passing through false but I'm not getting any errors.