[@Lucius Cypher] 
 
     Have you ever read like, forgotten realms or stuff like that? Well I figured one of the first things she would need is a object to bind it to so it can remain here. Just like how Drizzt's Panther is summonable due to the onyx statue he carries. The summoned creature can remain as long as he wanted but she would get weaker and weaker every hour she did and would have to return to her realm to rest. 

 During the ritual Vivian would have to first discover the spider's name. Then call out to it in the summoning ritual with the circles surrounding the object. Once the creature is summoned she would have a small window before it vanishes again to start the second part of binding it to the object. Once bound it could remain in our realm for as long as Vivian wants but every hour it's str stat will go down and down and it would begin to feel weaker and weaker to the point she would have to send it back into the object. Due to the object and the ritual the spider would have gain it's own plane of existance where it rests.