A post can be stackable and yet receive many downvotes, just as the opposite can happen
A question or answer is flagged when it does not fit the stack format, i.e., the question presents some of the flagable problems - Too Broad, Off-topic, Unclear, Opinion-based. Your question presents none of these problems, thus it's not flagged.
On the other hand, votes/scores are completely orthogonal to that and present how useful and well made a post is, according to the reader and, with enough votes, according to the community.
Obviously a post that is bad for the format usually will receive downvotes as well, as it is seen as not useful, e.g. How can I improve Views and likes for my gaming
Now, about your question, although I did not downvote, I only didn't because I don't like to downvote questions - actually, if you go through my stats, I don't like to downvote, period. A few reasons I would downvote if I was more trigger happy with the down arrow:
- It presents a seemingly unrealistic problem/scenario which is likely to be seen as "not useful" - for me it is.
- It's unclear what is the actual problem you want to solve. You want to summon the creature just because you can, or are you summoning it for another reason? If it's for another reason, it is indeed a case of XY Problem.
- It leaves us to imagine "what other issues might arrive", and since the scenario is, as I mentioned earlier, probably unrealistic and not useful, people don't have experience with it to actually know which problems might arrive.
- Even if they did, "What issues might arrive?" is usually a worse question than "I tried this and I had this problem, how can I solve it?", in your case, "I tried to summon a creature with Gate and this, this and this happened and my wizard got killed. How should I fix it?" - i.e., hypothetical questions are worse than questions based on an actual problem you faced.
Probably there are more issues with the question, to be honest, but these are enough for most trigger happy people downvote a question.