Spell for summon a monster

[Elizabeth]

hello

can please someone help me with a spell for summon one monster..

like the utevo res but this spell will summon only 1 monster in special.. no more..

i need it have limit of 1 monster... if the player summoned that monster, cant summon other until the actual summon still alive..

thanks

 

[Darkhaos]

function onCastSpell(cid, combat, var)
local summon = doCreateMonster("Demon", pos)
doConvinceCreature(cid, summon)
end