Since I've just met Stenriya for the first time in the campaign, I'm curious about something: do you actually need to eliminate Doh-Gor to get the key from her when you conquer her world, or is that only necessary to get her to admit to having it (so you can just go straight to declaring war as soon as you meet her)?

I'm still curious about this - do you actually need to eliminate Doh-Gor and thereby get Stenriya's confession in order to get the key from her, or can you just attack her directly to get it even though you don't yet "know" she has/is it?

When does the old man visit you? I'm 15 shards in (beginner difficulty), and the masters told me about the keys 2-3 shards ago. I'm starting to wonder if I might have missed the mission announcement (since the events get quite repetitive, I often "fast forward" some of the most frequent ones without really reading them...)

It seems to vary a bit, but happens sometime around then. I don't know if you'll ever get a second chance if you miss it, although since obtaining the key relies on clearing the temple the old man names, you could still get it even if you didn't realize what he was talking about.

You will obtain a scroll (or two) talking about the keys before you get your chance to find the first part, and you'll definitely know if you obtain it: there's only a small event in the shard but there's a more substantial one in the Astral afterward.

Thanks!
For now, I've only heard rumors about them and discussed them with the other masters. I'll be watchful for the next couple of shards, then.

I would like to know this as well.

AFAIK if you attack her without killing D'oh-Gor, she would disappear "unlike other masters" and wouldn't appear again. So, key will be missed.

Thanks!