If it's a demon, warning don't summon it. Some are malevolent. There are few benevolent. If it's a mythical creature, you can summon it as a spirit. They are not physical. Of it's a deity, and you have no connection with him or her, don't summon. Also summoning is tearing a entity from its realm to here our realm. Only summon if you have to. Never summon just to do it.