The strongest castle in Heroes of Might and Magic IV.

Well, there are different types of artifacts. For example, in the upcoming update, collecting 5 of Bob's artifacts will destroy all magic resistance, so there's no point in mentioning artifacts, as different situations can occur.

In principle, you are right. It all depends on the situation. Sometimes, the "general dispel" spell won't appear. And, accordingly, there's no guarantee that the "amulet of nature" will appear. It all depends on the situation, but I'm just presenting a theory... in practice, everything becomes more complicated.