Lua adding isWalkable function into a spell

[luigilc]

How can I check the function isWalkable:

function isWalkable(pos, creature, proj, pz)-- by Nord
	if getTileThingByPos({x = pos.x, y = pos.y, z = pos.z, stackpos = 0}).itemid == 0 then return false end
	if getTopCreature(pos).uid > 0 and creature then return false end
	if getTileInfo(pos).protection and pz then return false, true end
	local n = not proj and 3 or 2
	for i = 0, 255 do
		pos.stackpos = i
		local tile = getTileThingByPos(pos)
		if tile.itemid ~= 0 and not isCreature(tile.uid) then
			if hasProperty(tile.uid, n) or hasProperty(tile.uid, 7) then
				return false
			end
		end
	end
	return true
end

into this script:

local combat = createCombatObject()
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 + maglevel) * getPlayerMana(cid) / getPlayerMaxMana(cid)) * 2.9
	max = ((level + maglevel) * getPlayerMana(cid) / getPlayerMaxMana(cid)) * 3.2
	return reduceSpellDamage(cid, min, max)
end

setCombatCallback(combat, CALLBACK_PARAM_LEVELMAGICVALUE, "onGetFormulaValues")

function onCastSpell(cid, var)
	if(math.random(1, 2) == 1) then
		time = -1000
		for i = 1, 5 do
			addEvent(doMoveCreature, time + 1000, variantToNumber(var), math.random(0, 3))
			time = time + 1000
		end
		doCombat(cid, combat, var)
	else
		doSendMagicEffect(getPlayerPosition(cid), CONST_ME_POFF)
		doCreatureSay(cid, "The spell cast has failed.", TALKTYPE_ORANGE_1)
	end
	return true
end

cuz rght now, it is sending monsters inside the temple and beyond the map borders