I don't think Jojo, or Charlie, had anything at all to do with the Summon spell. I find it interesting that two separate casters from Unaroyal are working with Charlie, after their last orders being to only aide Royal sides. That also brings up an interesting point. Could it have been a 3-way link that created both the [edit: return home] scroll and the forced end turn casting? I'm not sure that just a turnamancer/thinkamancer (even with Artifact bonus) could have pulled that off. It should have taken a Carnymancer to break that rule. (wild speculation)
Also, I don't think Jojo was predicted to do anything. However, his casting caused Sylvia's fate to be as deterministic as if it Were Predicted. She was the "DM's girlfriend", in a way. That is some pretty powerful Fate magic right there. Let's just change some rules real quick, but not tell her about the specifics. She knew her fate, in the way that every unit knows their fate... intuitively. She even comprised a poem about it, and it is eerily prophetic (good job Titans, well played).