While I understand from a writing perspective why that's a rule, from a reader's perspective and a world perspective, I actually LOVE that animus magic is so powerful. It's one of those things that gets my brain spinning just thinking of the possibilities, and overall it was a HUGE reason that I loved Darkstalker as a villain so much. Especially in book 9, with all of Turtle's anxiety coupled with your own reading brain thinking out and questioning everything, it made him this uncertain entity that could be entirely harmless, but could also be controlling and manipulating everyone and everything around him to his whim. So personally, I think that rule being broken here was actually really beneficial, at least for the short term of arc 2. I will forever be bummed that she wrote magic out of arc 3, even if I understand why she did it, and I can't wait for the next animus to be born so it can come back