-- Reference to your ActionEvent
local actionEvent = game.Workspace.CHANGEUSER.Grab.ActionEvent -- CHANGE THE USERNAME

-- Loop through all descendants in Workspace
for _, obj in pairs(game.Workspace:GetDescendants()) do
    if obj:IsA("Humanoid") then
        local args = {
            [1] = "Zahvat",   -- your action type
            [2] = obj         -- the humanoid
        }
        actionEvent:FireServer(unpack(args))
    end
end