Rune in Invisible Monster

[bpm91]

Good night, I have an old school version, and my monsters don't take rune damage when they're invisible. I tried to build a script but it didn't work, I need the function to release the rune in order to hit an invisible monster - TFS 0.4

local combat = createCombatObject()
setCombatParam(combat, COMBAT_PARAM_TARGETCASTERORTOPMOST, true)
setCombatParam(combat, COMBAT_PARAM_TYPE, COMBAT_DEATHDAMAGE)
setCombatParam(combat, COMBAT_PARAM_EFFECT, CONST_ME_MORTAREA)
setCombatParam(combat, COMBAT_PARAM_DISTANCEEFFECT, CONST_ANI_SUDDENDEATH)

function onGetFormulaValues(cid, level, maglevel)
min = (level * 1.5 + maglevel * 2.0) * 2
max = (level * 1.8 + maglevel * 2.0) * 2

if min < 250 then
min = 250
end

return -min, -max
end

setCombatCallback(combat, CALLBACK_PARAM_LEVELMAGICVALUE, "onGetFormulaValues")


function onCastSpell(creature, variant, isHotkey)
local tile = Tile(Variant.getPosition(variant))
if tile and tile:getTopCreature() then
return combat:execute(creature, var)
end

creature:sendCancelMessage("You can only use this rune on creatures.")
creature:getPosition():sendMagicEffect(CONST_ME_POFF)
return false
end