Go to \data\actions\scripts and create a new file and call it manarune.lua
add this into manarune.lua:
local mana = 400
local say = "Aaaah..."
function onUse(cid, item, fromPosition, itemEx, toPosition)
if isPlayer(cid) then
doPlayerAddMana(cid, mana)
doCreatureSay(cid, say...