Harris

This relates to his experiments I guess?

I don't know how exactly to handle spoilers, so i'm going to be subtle.

Who targeted Notum outside Lasting Integrity? Why? I don't think we ever get an explanation for that

There are many theories, but the fact that Wit was presented as terrified implies he had not expected this to happen and he was not prepared for it in any way.

I as well do not understand why Wit would choose to show himself to Odium, there's nothing to be gained by boasting at this time.

Furthermore, while the initial contract included Wit protection, i dont recall the final contract protecting him in any way, so why risk facing Odium now? He was so certain of having him bested he couldn't wait 10 days? It sounds ridiculous.

More thoughts: why the story in the end and the talk about misdirection? They can't be just randomly placed in the book? Even if someone could take them as a forshadowing of his failure, it doesn't fit with how he was bested.

The clearest way i could interpret this moment (and the previous ones with Todium) is that it serves to highlight how dangerous the new Odium is.

Finally - and not really relevant - how can the god of passions not have the king of passions, love while representing its opposite, hatred?

The duel is 'to the death' so if Danilar puts himself as champion he ensured he is dead

The Hero of Ages has one of the best (probably the best indeed) closure you can find in a book series. 

So many questions answered, everything falling into place, ending unpredictable but not too far fetched. 

I would never rate it last in the series.