Possibilities for what will be the S3?

IshanK11 said:
Raihousha-hen is finished. Although some details were skipped/changed, the anime did adapt it. The next arcs in the light novel are the Double Seven arc, the Steeplechase arc and the Ancient City Insurrection arc. Double Seven and Steeplechase are both one volume each, so they shouldn’t take over 5 episodes each to adapt. Ancient City Insurrection is 2 volumes and is packed with details, so it would probably take about 9 episodes to adapt properly. I’m not sure which arcs will be adapted and which ones will be skipped if a season 3 is announced, but Double Seven arc is the one I’m guessing would be skipped if a 13 episode new season was announced. Hope that helped.

IshanK11 said:
Yes, there is an arc called Master Clans Conference arc. It spans 3 volumes and is slightly further ahead in the series. To clarify this, the Ancient City Insurrection arc covers volume 14 and 15 of the Light Novel. Volume 16 is the Yotsuba Succession arc and the Master Clans Conference arc consists of volume 17, 18 and 19. So it definitely wouldn’t be adapted in season 3.

I’m not sure what your second question is, but I’ll try and answer what I think it is. Raihousha-hen was adapted in the first 11 episodes of season 2. The last 2 episodes of this season adapted an spin-off type story written by the author of Mahouka Koukou no Rettousei. So Raihousha-hen ended with episode 11 of season 2. Some content from the light novels was skipped and some of it was changed slightly, but overall the arc was adapted well. The end of season 2 was a scene from the start of the Double Seven arc, which implies that the arc may be covered in season 3.