Abyssal Creature

The way by which you can tap into the abyss with the summoning plane is called a summoning duel. As a summoner, you can use a special ritual to open up a portal that would link to the abyss. 

From that portal, an abyssal creature will come out and will battle you in the summoning plane. You must subjugate it if you want to win and make it your summon. 

The message ended there without any further detail, not even the spell that Silva was to use, but he was eager to try it out. So, immediately, he called out the system to help him. 

"System, give me the summoning ritual, now." 

[Summoning ritual, hidden spell initiated.] 

It seemed he always had this particular spell as well, but like the other things, it was hidden. The information from the spell poured into his head, and in a few seconds, he knew exactly what to do.