Bug animated dead rune

[Sigoles]

Hello, I think this rune is bugged, cuz the normal is only two monsters, no more right?

Script, spell:

function onCastSpell(creature, variant, isHotkey)
    local position = Variant.getPosition(variant)
    local tile = Tile(position)
    if tile and creature:getSkull() ~= SKULL_BLACK then
        local corpse = tile:getTopDownItem()
        if corpse then
            local itemType = corpse:getType()
            if itemType:isCorpse() and itemType:isMovable() then
                local monster = Game.createMonster("Skeleton", position)
                if monster then
                    corpse:remove()
                    monster:setMaster(creature)
                    position:sendMagicEffect(CONST_ME_MAGIC_BLUE)
                    return true
                end
            end
        end
    end

    creature:getPosition():sendMagicEffect(CONST_ME_POFF)
    creature:sendCancelMessage(RETURNVALUE_NOTPOSSIBLE)
    return false
end