module.lua

-- Original code
tpz = {}
tpz.mob = {}
tpz.mob.onAttack = function(amount)
    return amount
end

print('Original call: ', tpz.mob.onAttack(100))
-- Prints 100

-- 'Module' helper
module = {}
module.override = function(base_table, name, func)

    local old = base_table[name]
    local thisenv = getfenv(old)

    local env = { super = old }
    setmetatable(env, { __index = thisenv })

    setfenv(func, env)
    base_table[name] = func
end

-- Module content
module.override(tpz.mob, "onAttack", function(amount)
    return super(amount) * 1.5
end)

-- Runtime call
print('Call after module applied: ', tpz.mob.onAttack(100))
-- Prints 150