"How to do something" questions are typical for most practical discussions. They are perfectly fine, until:
- OP can actually do this and check if that does solve his/her problem
- OP can see how many people do the same thing and what long-term results do they have
- We can compare our results and come co conclusion, what method is better and why
In a fantasy setting the only criteria is - does the author like it or not, which is the definition of "opinion based". He can like an option because it looks plausible for him, or it looks cool, or because it gives more ideas for the plot. There are no other means to determine which way is actually the best.
I have a magic device/ability X.
What would be the best way to do Y with it, in my fictional country of Z?
Even when you describe how the device works, what possibilities and limitations does it have, there will be a context that changes everything. If we are talking about a magical, fantasy, not science-based setting, nobody can deside which way would be the best, its always up to the author. As the result, we don't have a strict answer, but a bunch of ideas/opinions instead.
Examples of "how to" questions: