Why does this outscore function not work?

You need to change the block variable to global (or define the local variable at the beginning and set it there). Your onHumanoidDied function can't see block. Also, you can consolidate the two if statements on lines 25 and 28. Once that's fixed, it'll look something like this.

local isAdmin = {["Incrility"] = true}
local block --make block a local variable for faster look up, but available to the entire script.

--[[function findPlayer(name) --This function is not used in this script whatsoever. I have no idea why it's here.
    for _, player in ipairs(game.Players:GetPlayers()) do
        if player.Name:lower() == name:lower() then
            return player
        end
    end
end--]]

function onChatted(message)
    if message:sub(1, 10) == "!outscore " and isAdmin[player.Name] then --if an admin chats !outscore
        block = (message:sub(11)) --get the number after the message 
    end
end 

function onHumanoidDied(humanoid, player)
    local stats = player:findFirstChild("leaderstats")
    if stats then --this is a simplified way to check if something exists. If it's nil, it'll return false and not run the code
        local deaths = stats:findFirstChild("Wipeouts")
        deaths.Value = deaths.Value + 1
        if deaths.Value > block then --this is only needed once.
        player.TeamColor=BrickColor.new("White") 
        --a = game.Players:GetChildren() --"a" isn't used anywhere
        pack=game.StarterPack:GetChildren()
        if #pack>0 then
            for i=1,#pack do
                pack[i]:destroy() --don't forget that this is the StarterPack for all players, not just the one who met the criteria. Also, you might want to make sure the character doesn't respawn until you change the StarterPack if that's what you really want to do.
            end
        end
    end 
end

game.Players.PlayerAdded:connect(function(player)
    player.Chatted:connect(function(msg) onChatted(msg) end)
    player.CharacterAdded:connect(function(character)
        character:WaitForChild("Humanoid").Died:connect(function()
            print(player.Name .. " has died!")
            onHumanoidDied(character.Humanoid, player)
        end)
    end)
end)

This code has not been tested.

local isAdmin = {["Incrility"] = true}

local block --make block a local variable for faster look up, but available to the entire script.


function onChatted(message)

    if message:sub(1, 10) == "!outscore " and isAdmin[player.Name] then --if an admin chats !outscore

        block = (message:sub(11)) --get the number after the message

    end

end


function onHumanoidDied(humanoid, player)

    local stats = player:findFirstChild("leaderstats")

    if stats then --this is a simplified way to check if something exists. If it's nil, it'll return false and not run the code

        local deaths = stats:findFirstChild("Wipeouts")

        deaths.Value = deaths.Value + 1

        if deaths.Value >= block then --this is only needed once.

        player.TeamColor=BrickColor.new("White")

        --a = game.Players:GetChildren() --"a" isn't used anywhere

        pack=game.StarterPack:GetChildren()

       if #pack>0 then

            for i=1,#pack do

                pack[i]:destroy() --don't forget that this is the StarterPack for all players, not just the one who met the criteria. Also, you might want to make sure the character doesn't respawn until you change the StarterPack if that's what you really want to do.

            end

        end

    end

end
end


game.Players.PlayerAdded:connect(function(player)

    player.Chatted:connect(function(msg) onChatted(msg) end)

    player.CharacterAdded:connect(function(character)

        character:WaitForChild("Humanoid").Died:connect(function()

            print(player.Name .. " has died!")

            onHumanoidDied(character.Humanoid, player)

        end)

    end)

end)

I recopied it i think i might have changed something dont really know but the script does not work... I do appreciate the answer though. I got no error in output and when i played game and executed it didnt work.