(original title: "How to artfully min-max the hell out of this verstatile fighting style and feat?")
So, given all the answers to my previous question, we have come up with what we think hope is a balance fighting style, and an accompanying feat, for fighting with versatile weapons.
Note from the chat:
I would like to know if the combination of this fighting style and feat is balanced in general; not if it balanced for specific builds.
Just like Two-weapon fighting was not written for a specific build: it is a generally available fighting style, that can be used by different builds. The same goes for Dueling, and Great Weapon Fighting.
I asked the question in this same light.
Background
Because we feel fighting with a versatile weapon, seamlessly switching between one- and two-handed wielding, is an iconic style of fighting, that is under-represented in D&D. This is because the rules favour either sword-and-board or great-sword wielding brutes. Yes, you can wield a longsword with either Great Weapon Fighting or Dueling, but we feel that both fall short on the versatile-part.
So, we intend this fighting style to be an alternative to the existing melee fighting styles (Two-Weapon Fighting, Dueling, and Great Weapon Fighting), that it provides flavourful option, to those character that it appeal to, without disrupting the balance of the existing rules.
Fighting style
Versatile Fighting
When you are wielding a versatile weapon with which you are proficient, and no other weapons or shield, you gain the following benefits:
- You gain a +2 bonus to damage rolls1).
- When another creature hits you with a melee attack, you can use your reaction to add your proficiency bonus to your AC for that attack, potentially causing the attack to miss you.
Feat
Versatile Mastery
When you are wielding a versatile weapon with which you are proficient, and no other weapons or shield, you gain the following benefits:
- When you wield your weapon with one hand, your weapon has the reach property.
- Before you make a melee attack, you can choose to take a -3 penalty to the attack roll. If the attack hits, you can make an additional melee weapon attack, with the same weapon, as a bonus action.
Design intentions
We wanted a set of rules that are easy to understand, and easy use. The rules should provide an interesting option to character classes with access to fighting styles, that is different enough in flavour to merit its existence. It should be strong enough to be a valid, competitive choice, while at the same time not so strong that it overpowers the existing fighting styles.
However, D&D has many rules that seem balanced enough on their own, but, when artfully min-maxed, can be turned into a game-breaking monster.
We feel relatively confident about the Versatile Fighting fighting style on its own being fairly balanced, and less certain when the Versatile Mastery feats comes into play.
So, my questions are:
- Is this fighting style, and the accompanying feat balanced?
- Can these rules, when combined with other rules, become too strong?
Appendix I: Average Damage per Round, formula
The Average Damage per Round without the Versatile Mastery feat is rather straight forward, so I'll not explain it here. The Average Damage per Round with the Versatile Mastery feat is rather more complicated, and can be calculated as described below.
Please refer to MannerPots's answer, for a complete explanation of the math involved. What follows here is a slightly adapted version of the formula given in his answer:
Let \$n\$ be the number of regular attacks, \$p_n\$ be your chance to hit, \$p_p\$ be your chance to hit with -3 penalty, \$p_c\$ be your chance to crit, \$d_n\$ be your damage on a normal hit and \$d_c\$ be your extra damage on a crit.
Then the expected damage of a normal attack is \${p_n}d_n + {p_c}d_c\$.
The expected damage of an attack with a -3 penalty is \${p_p}d_n + {p_c}d_c\$.Then the total Average Damage per Round is:
$$\sum_{i=0}^{n-1}(1-p_p)^{i} \left({p_c}d_c + p_pd_n + p_p(n-i)({p_n}d_n + {p_c}d_c) \right)$$
Appendix II: Average Damage per Round, pre-calculated
Table 01: Versatile Fighting (1d10)
| Hit probability | 1 attack | 2 attacks | 3 attacks | 4 attacks | 5 attacks |
|---|---|---|---|---|---|
| 5% | 0.850 hp | 1.700 hp | 2.550 hp | 3.400 hp | 4.250 hp |
| 10% | 1.425 hp | 2.850 hp | 4.275 hp | 5.700 hp | 7.125 hp |
| 15% | 2.000 hp | 4.000 hp | 6.000 hp | 8.000 hp | 10.000 hp |
| 20% | 2.575 hp | 5.150 hp | 7.725 hp | 10.300 hp | 12.875 hp |
| 25% | 3.150 hp | 6.300 hp | 9.450 hp | 12.600 hp | 15.750 hp |
| 30% | 3.725 hp | 7.450 hp | 11.175 hp | 14.900 hp | 18.625 hp |
| 35% | 4.300 hp | 8.600 hp | 12.900 hp | 17.200 hp | 21.500 hp |
| 40% | 4.875 hp | 9.750 hp | 14.625 hp | 19.500 hp | 24.375 hp |
| 45% | 5.450 hp | 10.900 hp | 16.350 hp | 21.800 hp | 27.250 hp |
| 50% | 6.025 hp | 12.050 hp | 18.075 hp | 24.100 hp | 30.125 hp |
| 55% | 6.600 hp | 13.200 hp | 19.800 hp | 26.400 hp | 33.000 hp |
| 60% | 7.175 hp | 14.350 hp | 21.525 hp | 28.700 hp | 35.875 hp |
| 65% | 7.750 hp | 15.500 hp | 23.250 hp | 31.000 hp | 38.750 hp |
| 70% | 8.325 hp | 16.650 hp | 24.975 hp | 33.300 hp | 41.625 hp |
| 75% | 8.900 hp | 17.800 hp | 26.700 hp | 35.600 hp | 44.500 hp |
| 80% | 9.475 hp | 18.950 hp | 28.425 hp | 37.900 hp | 47.375 hp |
| 85% | 10.050 hp | 20.100 hp | 30.150 hp | 40.200 hp | 50.250 hp |
| 90% | 10.625 hp | 21.250 hp | 31.875 hp | 42.500 hp | 53.125 hp |
| 95% | 11.200 hp | 22.400 hp | 33.600 hp | 44.800 hp | 56.000 hp |
Table 02: Versatile Fighting (1d10), with Versatile Mastery
| Hit probability | 1 attack | 2 attacks | 3 attacks | 4 attacks | 5 attacks |
|---|---|---|---|---|---|
| 5% – 45% 2) | … | … | … | … | … |
| 50% | 6.409 hp | 12.683 hp | 18.870 hp | 25.001 hp | 31.094 hp |
| 55% | 7.515 hp | 14.664 hp | 21.593 hp | 28.391 hp | 35.110 hp |
| 60% | 8.679 hp | 16.681 hp | 24.311 hp | 31.736 hp | 39.048 hp |
| 65% | 9.900 hp | 18.725 hp | 27.013 hp | 35.031 hp | 42.916 hp |
| 70% | 11.179 hp | 20.788 hp | 29.691 hp | 38.276 hp | 46.718 hp |
| 75% | 12.515 hp | 22.861 hp | 32.339 hp | 41.471 hp | 50.463 hp |
| 80% | 13.909 hp | 24.936 hp | 34.954 hp | 44.619 hp | 54.160 hp |
| 85% | 15.360 hp | 27.003 hp | 37.531 hp | 47.724 hp | 57.817 hp |
| 90% | 16.869 hp | 29.055 hp | 40.070 hp | 50.792 hp | 61.442 hp |
| 95% | 18.435 hp | 31.082 hp | 42.571 hp | 53.829 hp | 65.041 hp |
1) To avoid confusion, I will not change the wording of the question. However, as stevenjackson121 already suggested, this bonus is intended to only apply to the versatile weapon in question. So this bullet point should read: "You gain a +2 bonus to damage rolls with that weapon."
2) It only makes sense to attempt to trigger the bonus attack, for a hit probability of \$50\%\$ or higher.
Best Answer
There is at least one Exploitable Edge Case
There are several minor, but important differences in the wording of your fighting style and the accompanying feat compared to official options that seem exploitable. I recommend going over the language used in official feats and trying to match it as closely as possible to prevent cheese unique to your new fighting style and feat.
Versatile Fighting For Monks and Spellcasters
Dueling says
While Versatile Fighting says
As written, this would apply to a monks unarmed strikes made with the free hand or another body part, or spells/cantrips. Both can make multiple attacks per round (Scorching Ray, Eldritch Blast, Flurry of Blows, etc.) that would provide a larger benefit than intended.
This is especially important because Monks and Gish characters are probably going to be attracted to the feat in the first place (the ability to gain defensive benefits without a shield is good for both, and being able to switch between "focus + sword" or "2h grip on sword" is a possible gish option).
Versatile Mastery For Glass Cannons/Gishes
This isn't necessarily an exploit, but this feat will probably not support the playstyle you intend. Characters will not likely utilize both 1 handed and 2 handed options against the same opponent (either it's an opponent they're fine duking it out with using 2h from 5 ft., or they're an opponent that needs to be kited and killed with only 1h).
This may even be attractive for characters who never intend to use the 2h option. Reach is usually only available on martial weapons, and even among those only the Lance (which has its own drawbacks), Whip (which has terrible damage), or weapons with both the two-handed and heavy property have Reach. Introducing a way to get Reach on simple melee weapons wielded in one hand makes the trait vastly more accessible, and may be worth a feat for certain builds.
A Rogue would strongly benefit from the ability to use the Sun Blade for example, which has both Finesse and Versatile, to reliably sneak attack from 10 ft away and then retreat while reserving their bonus action for Steady Aim (If mounted), or a subclass feature (like Use an Object for Thief).
Outside of reach, BladeSingers (as one example) can use versatile weapons but can never attack with 2h or use shields, and may just always hold a focus in the off hand. This feat might still be worthwhile to pick up just for reach.
Different Enough to Merit Existence?
Great Weapon Master gives the opportunity to earn a bonus action attack on your turn, and also gives the opportunity to sacrifice hit chance for damage. The current 2nd bullet of Versatile Mastery basically rehashes this same tradeoff.
Similar to Great Weapon Master, the feature will only be useful against enemies you already need a 20 to hit (extremely high AC) or enemies that are very easy to hit (low AC) and poor in the middle.
I recommend trying to give a bonus that currently doesn't exist in melee, such as the to-hit bonus present in Archery Fighting Style, which is much more effective against mid-range ACs and least effective against extremely high ACs (which can only be hit with a 20 regardless) and very easy ACs (going from 80% to 90% changes DPR by a much smaller percentage than going from 25% to 35% chance to hit).
Tying this bonus to explicitly changing stances will help it remain a flavorful option for a specific playstyle, rather than being a feat pure 1h characters take to get a unique benefit more than actual versatile characters.
Recommendation
Clean up the language for the fighting style so the damage bonus only applies to the weapon in question.
For the feat: at minimum, add a bonus for either switching or add a bonus that's only accessible when attacking with 2h. Maybe the initial hit in the second bullet must be made with 2h to get the bonus action attack, or maybe you don't provoke opportunity attacks from enemies you attack with 2h.
I'd consider a full rework more along the lines of:
The "bonus attack on miss" helps make damage output more consistent (contrasted with the swingy all or nothing nature of GWM damage output) and ensures the first 2 bullet points can occasionally be used by any character even before extra attack. Misses will happen frequently against tough opponents from level 1 all the way through level 20, especially for martials who make a high number of attacks.
The first 2 bullets offer two ways to structure your turn, roughly: a higher damage mode for easy to hit opponents, or a higher hit chance mode for other opponents. The +2 to hit is likely to be stronger most of the time, and that's good because that differentiates the feat most from other melee options (and even from sharpshooter) by prioritizing consistency. The +2 damage is more of a flavorful addition and to add versatility.
Ensuring the benefits are tied to stance changes also ensures edge cases involving pure 1h characters or pure 2h characters abusing the feat are prevented entirely.