I have a level five fighter who enjoys using the terrain as a weapon in a somewhat WWE style. I am at a loss as to how to go about adjusting the damage he does for the less than by-the-book actions.
My last game session he pulled a monster off the edge of a 10-foot cliff from below, and, as they put it, "put all their body weight into slamming them into the ground". I enjoy the flavor, and in and of itself it's fine, but the only math I have that is supported by the book is fall damage + his strength mod with a d4 for an improvised weapon. I am getting the impression that it feels like a very lackluster bit of damage for them overall, and will become even more of an issue as the character gets higher level where normal attacks do more damage.
(As it stands now he's just done this where he would have been able to make normal attacks already — sometimes going as far as putting away the sword and shield to do so — so I am not worried too much about him being a munchkin.)
My ultimate question is, how do I give the character more damage with these improvised actions as they progress, while keeping balance for the other characters?
Strength +3 vs. +5 is not much improvement compared to 3 or 4 extra attacks. The situations overall will remain unchanged in that he's not really ever going to be able to jump higher (barring magic) than that 10-foot wall, so fall damage from this tactic would remain static. Proficiency added to the damage for this type of action might solve that.
Page 249 of the DM Guide has an improvised damage chart but most of it feels too static.
My goal is not full narrative combat, but more to find a happy middle ground so that one of my five or so players does not hate his class just because it's less flavorful than being able to throw fireballs, and I want to find that middle ground without also breaking everything. I am kind of new, as a DM, to be houseruling too much — I simply don't feel like I have a good enough grasp on the system to not break things.