Where the hell is it hiding? This is the single most blatant thing I have ever seen, with the original description saying that this is dangerous, most people in universe are not arrogant enough to attempt it when there are better versions around, and it should backfire.
Except for vast majority of sorcerers in Creation, there
is'nt a better version around. Offhand, there are around 1,000 sorcerers in the Realm alone, 400 of which are actually dedicated. The entire Lunar+Sidereal hosts number 400, and not all of them are sorcerers, let alone Sapphire Circle Sorcerers.
There are far more Dragon-Blooded around who know sorcery, as well as mortal sorcerers. In games that have more Dragon-Blooded around than canon's 10,000 for the Realm in total, you would have even more sorcerers.
In over 700 years since the Contagion, how many sorcerers do you think there would be? I realize ES intends this for the arrogant and hubristic character, but I don't think he fully considered the
desperate character or the one who calculates risk-vs-reward. Think of how many wars or disasters in Creation would have a sorcerer benefit greatly from having a 2CD, or even allow them to survive at all. Sometimes a sorcerer could attempt this not because they are arrogant, but because
they don't have a better option.
And when you bring that into play, you have others reacting to it. Consider a Dragon-Blooded Outacaste who's kingdom is invaded by the Realm. She desperately wants to save her homeland, and in desperation summons Octavian. "Ok", you think, "this is working as intended". Except now the Dynast commanders have to take this option into account. They might even decide that, with a couple dozen DB's around, including a group of Immaculate martial artists, they like their chances even if it backfires and summon their own 2CD. For this one war, the paradigm holds, more or less: a desperate sorceress summoned a being she could not fully control. A desperate Dynast general summoned his own 2CD in response.
Except now, its precedent. Next time, the Dynast commander will consider using a bound 2CD in a future encounter just
in case the enemy is capable of summoning their own 2CD. Over time, the commander and his subordinates get pretty good at this. They use the same demons, they learn their tricks, they keep a significant amount of resources on hand to be able to deal with them. Sometimes it goes bad, and they have to fight a 2CD. Many other times, it works fine. They settle into a new routine, one where they are able to assess the risk of failure versus the reward of having a mostly reliable 2CD on their side.
You end up with a setting that will get used to the idea that you can summon a 2CD and has learned to work with it, because it lets any sorcerer potentially summon a 2CD. It is no longer the thing that happens once in a generation and becomes legend and a lesson in the Heptagram "this is why we don't summon 2CD's". It becomes routine. Risky, but people do risky shit on a routine basis all the time for the chance at high reward
This is my opinion, based on my own experience (which I admit is'nt much, since I only played one game for the past 2 years). Yeah, most players may look at this and go "nah, this is begging for trouble", but the
setting as a whole will learn to live with it. This is why I believe this breaks the setting too much.