I've been running Dungeon World games for two years now and from my experience, once a player's dominant combat ability scores reach 18, it becomes very difficult for opponents to put up a fight against them. In Dungeon World, the GM can directly influence the story when one of the following happens:
- When everyone looks to you to find out what happens
- When the players give you a golden opportunity
- When they roll a 6-
Once an ability score reaches 18, rolls associated with it average out to 10. Thus, it seems that triggering that 6- clause becomes increasingly less likely, requiring a roll of 3- on a 2d6 roll. When looking at the other two clauses, it would lead me to assume that the GM should also be making moves when players do not roll 6-, albeit said moves should lean towards the soft side to avoid taking away from player success.
However, most GM moves function by posing a challenge which a character must overcome, which often result in a player triggering a "Defy Danger" roll, which is typically aligned thematically with the triggering roll. Combat moves are met with combat moves, thus high ability scores, particularly physical ones, make characters unlikely to fail. As such, combat where characters are supposed to be outclassed usually boil down to a series of rolls where the worst outcome is a middling success before a solid hit is scored, or a series of solid hits with little or no pushback.
Articles explaining how to GM Dungeon World often cite the use of tags and narrative positioning to force players to shift their behavior against a threat. For instance, 16 HP Dragon posits that a dragon with the messy tag might shear off limbs when attacking foes, forcing players to keep their distance to avoid the danger. However, leaving aside that this could also be a hard move of its own right, it does not entirely solve the issue. With a 50% chance of completely successful moves (based on the average roll of 10), there is also a large chance that the opponent will simply never get to hit a player character, even with a middling success.
In the rare cases where a middling success occurs or in the very rare case of a failure, harsh punishment can come at a bit of a whiplash when a fight has been going completely smoothly before. Harsh punishment is in fact necessary for this model or it will not impact the scope of the fight enough to change play.
Ultimately, is this a fundamental misunderstanding of how the game should be played? Need challenging fights with characters with high stats require more devious means of combat than the usual slugfest?