D&D 5E The mathematics of Shield Mastery vs the -5/+10 feats

[Dausuul]

There are three huge problems with doing this as a white-room calculation:

• Advantage does not stack and can be obtained from a variety of sources. -5/+10 stacks with other damage modifiers.
• The power of GWM and Sharpshooter comes from their combo potential. By themselves, they are middling-quality feats. But when you stack on bonuses to hit and/or advantage, they become insanely good.
• Shield Master costs a bonus action while the GWM/SS bonus does not.

Because of all that, I think a white-room calculation would not merely be un-useful; it would be actively misleading, putting a heavy thumb on the scale for Shield Master.

If I were determined to do it, though... I would probably pull a list of the monsters in the Basic Rules from someplace, and make a spreadsheet to calculate the expected damage benefit of each feat versus each monster, then average them.

 

[WhosDaDungeonMaster]

Man, Shield Mastery is a hot topic lately

SO TRUE!

Anyway, another thing to consider outside of the mathematics comparison, is there are many foes you cannot "knock prone". Everything, to my knowledge, is subject to the +10 damage achieved through GWM or SS.

In comparing the two is Shield Master involves a check to knock prone first. If you rule the bonus action can come first, you could have one or more attacks at advantage. Given a better chance of hitting on such attacks you are more likely to do damage in the round. However, all things considered you are probably about as likely to succeed as fail on the Shove.

I think overall you will find them comparable and too much depends on the numerous factors such as opponent Str, AC, number of attacks available, if you have allies nearby who can also benefit by attacking a possibly prone target, etc.

Given a specific example and parameters, I could do the math, but with so many variables it would not be worth the effort.

 

[Quartz]

There was no indication in the original post that you were houseruling or were aware of the change, since it had flip-flopped a few months back.

Sorry; I was a tad harsh there. But different people read the rules differently. Not everyone keeps up with all of the latest Sage Advice.

 

[5ekyu]

This is incorrect. You just described something that is not allowed. The current ruling (and it's flip-flopped a few times) is that the bonus action has to take place AFTER the triggering action.

So your attacks go off, then you have a chance to knock prone. Sometimes between when you went and when you go again they get their action, which they can use to get up.

Now, it can add to your allies being able to hit more, at least the ones that go between your action and when the target gets up.

If it was correct (like it was in the past), you need to not only see the bonus it gives you, but also the bonus it gives your allies. That can be pretty extreme such as in a solo fight, but it's very context dependent.

Or you can shield bash to prone then action surge... Or a lot of other uses.

 

[Dausuul]

Sorry; I was a tad harsh there. But different people read the rules differently. Not everyone keeps up with all of the latest Sage Advice.

Also, Sage Advice rulings are not official errata. They are merely, as the name implies, advice (and not always good advice IMO).

 

[FrogReaver]

The idea behind the Shield Master feat is that you bash and hopefully get advantage on your attacks, thereby hitting more often and doing more damage. The idea behind the -5/+10 feats is that you hit less often but do more damage when you do hit. How does the maths compare? How often does Shield Master actually give you advantage?

(Ignoring Critical Hits)
The relative impact of advantage on an attacks accuracy weighted damage is simple to calculate. For example if you have a 60% chance to hit without advantage then your relative increase in damage will be 100%-60% = 40%. This same calculation works for any accuracy value.

I think most characters have somewhere around a 50%-70% (avg 65%) chance to hit on most attacks, so in general I'd estimate advantage increasing attack damage by 35%.

Shield Master only has a chance to knock an enemy prone. Assuming Shield Master having a 50% chance to knock an enemy prone that's an average of a 17.5% increase in damage. Assuming an 80% chance to knock an enemy prone that's an average of a 28% increase in damage.

Now sometimes you may have advantage anyways in which case shield master doesn't help any. Sometimes you might fight a foe too large to knock prone with shield master causing it not to help any. If I had to estimate a single number as my shield master average for increasing damage I'd lean toward the low end of the damage range listed above. Thus, I think 17.5% damage increase would be the best estimate you can get without looking at campaign specifics.

Now, that's going to be a potential 17.5% damage increase for all your melee allies. However, prone causes ranged allies to have a lower chance to hit. Thus, I'd lower that 17.5%. Assuming 3 of 5 party members use melee attacks I would estimate about a 10% increase in party damage from shield master.

So the answer to the question IMO is about 17.5% increase in your individual damage and about 10% increase in party damage.

GWM tends to increase individual damage a lot more. It doesn't lower ranged allies damage and if it even increases your DPR by 50% then it's party damage increase is also about 10%.

Personally I think it's easier to optimize GWM at that point and push it higher than a 50% individual damage increase which starts making it be much better than shield master. Also PAM works with GWM giving you the opportunity to have 2 damage feats as opposed to a single one.

IMO, shield master is not a bad feat but it requires a melee heavy party, ways to increase athletics and some luck on fighting enemies of the proper size category before it starts mechanically performing anywhere near GWM combos.

 

[Spohedus]

This is the proverbial comparison of apples and oranges. Shield Mastery gives you territorial control of the battlefield, and may provide advantage to another melee party member (or disadvantage to a ranged party member). There are other nice uses of the knock back option for shoving, such as removing a mob from being able to hit a party member, knocking them into dangerous terrain, or restricting movement to half by knocking prone. Plus there is the damage reduction on things that require a Dex ST. GWM and SS increase damage. Their 2nd features (bonus action extra attack and ignoring cover) are actually pretty strong. The -5/+10 is situationally bad or amazing, which is cool for player choice/strategy. Comparing Shield Mastery to one of these comes down to what you want your character's role to be in the party.