... [A]ntagonists just seem downright stupid. You cannot possibly tell me that 'oh yes it is possible to defeat the magical spatial sniper simply by throwing mushrooms at them', do you think our antagonists do not have brains?
If the solution to the villains' problem (you) is
poison him or something, that they never do is baffling. "Oh, but I'm the safest in the Stadium, everyone would suspect she killed me!" Motherfucker, it's widely known both the Master of Ceremonies and principal owner are involved in every crime in town. Who do you think will
care if you're dead, especially after only 2-3 fights?!
The manga wants the trappings of financial and political stakes, but somehow ignores how those are threatened by him remaining alive between fights. Just kill him! If the new harem keeps saving him from assassins, bomb the whole building! He's emptying out your coffers and turning nobility against you,
act like it!