How to make a Combat Blocking Script?

So I was debating whether to answer this now or later, and here I am. Here's how you'll do it:

First off, you want to make sure that the player's character (or player) has a Value called "Blocking". How you can achieve this is by having a Script inside of 'StarterCharacterScripts'. Inside of the script (make sure it is a ServerScript and not a LocalScript), you would do;

wait();
local char = script.Parent;
local h = char:WaitForChilr("Humanoid");

local blocking = Instance.new("BoolValue");
blocking.Name = "Blocking";
blocking.Value = false;

Now that we have a bool set up (this is to protect as much as possible against exploitation), we will need the player to block. You would create a localscript inside of StarterGUI and have this in it:

local blockingKey = Enum.KeyCode.R;
local uis = game:GetService("UserInputService");
local p = game.Players.LocalPlayer;
local c = p.Character or p.CharacterAdded:wait();
local RF = game.ReplicatedStorage.RemoteFunction;
local response;

uis.InputBegan:Connect(function(key, gameProc) -- this is an event that fires when player presses a key
   if(key.KeyCode == blockingKey and not gameProc) then
       response = RF:InvokeServer(true);
   end
end)

uis.InputEnded:Connect(function(key, gameProc) -- this is an event that fires when player lets go after holding a key
   if(key.KeyCode == blockingKey and not gameProc) then
       response = RF:InvokeServer(false);
   end
end)

-- You can now start using 'response' in other functions, within this script.

Now, create a RemoteFunction in ReplicatedStorage. Then, make a script in ServerScriptService, and inside of it, include the following:

local RF = game.ReplicatedStorage.RemoteFunction;
local blockSpeed = 8; -- change this to how slow you want them to go when blocking

RF.OnServerInvoke = function(player, this)
   local c = player.Character or player.CharacterAdded:wait();
   local blocking = c:FindFirstChild("Blocking");
   assert(blocking ~= nil and c ~= nil, "Blocking and/or Character was not found.");
   local h = c:FindFirstChildOfClass("Humanoid");
   local oldSpeed = h.WalkSpeed;
   if(this) then
     if not (blocking.Value) then
       blocking.Value = true;
       h.WalkSpeed = blockSpeed;
       -- Load animation and play here
     end
   elseif this == false then
     if (blocking.Value) then
       blocking.Value = false;
       h.WalkSpeed = oldSpeed;
       -- Stop animation here
     end
   end
end

Now that we have a Blocking system set up, on your hitBox script (that makes players take damage), check if the hit char has a value called "Blocking" and if it's Value is true. If it is, make them take less damage. If it isn't, take normal damage.

That's the way I would do it.