local combat = createCombatObject()
setCombatParam(combat, COMBAT_PARAM_TYPE, COMBAT_HEALING)
setCombatParam(combat, COMBAT_PARAM_EFFECT, CONST_ME_MAGIC_BLUE)
setCombatParam(combat, COMBAT_PARAM_AGGRESSIVE, false)
setCombatParam(combat, COMBAT_PARAM_TARGETPLAYERSORSUMMONS, true)
setCombatParam(combat, COMBAT_PARAM_DISPEL, CONDITION_PARALYZE)

local area = createCombatArea(AREA_CIRCLE3X3)
setCombatArea(combat, area)

function onGetFormulaValues(cid, level, maglevel)

local percent = 50 -- 50 porcento

    local min = math.floor(getCreatureHealth(cid) * percent / 100)
    local max = math.floor(getCreatureHealth(cid) * percent / 100)

    return min, max
end

setCombatCallback(combat, CALLBACK_PARAM_LEVELMAGICVALUE, "onGetFormulaValues")

function onCastSpell(cid, var)

    if getPlayerItemCount(cid, ITEM) < 1 then
       doPlayerSendCancel(cid, "Sorry, not possible.")
       return false
    end

    doPlayerRemoveItem(cid, ITEM, 1)
    return doCombat(cid, combat, var)
end