Tuesday, February 20, 2024

Napkin Math: Deflect Attacks versus AC

 The most recent playtest of the Monk addressed many concerns - it gave Monks something akin to Cunning Actions by letting them dash or disengage as a bonus action for free and did a few other thing to make Discipline Point usage more efficient.

But one of the concerns I've always had with the Monk is their survivability in melee. Monks, along with Barbarians and Paladins, are the only class that really has to be in melee (while most Fighter builds are melee-focused, you can make a perfectly effective ranged build,) which puts them at two disadvantages - they need to get close enough to monsters to hit them, requiring navigating the battlefield, and also that it puts them in harm's way, setting them up for the monster to retaliate. The former, Monks are actually pretty good at, with their increased movement and various movement bonuses (like being able to run along walls and such). But while a Barbarian has the biggest hit die and Rage to halve the damage they take from most melee strikes, and Paladins can strap on a shield and plate armor to have a very high AC, Monks often have a lower AC and lower HP than their melee comrades.

Deflect Missiles has been part of the Monk's feature list since 2014, and it's very cool, but tends to only come into play if you're fighting humanoid enemies that aren't flinging magic at you. Most inhuman monsters will stick to melee attacks, and at higher levels of play, ranged attacks will often be spell attacks rather than arrows and crossbow bolts. There are occasionally spines and needles tossed by various fiends and such, but these are less common.

In the latest playtest, though, Deflect Missiles got a massive upgrade - it became Deflect Attacks, and at higher levels, it allows the deflection of attacks of practically all damage types.

The math for the feature is the same - you use a reaction to reduce the incoming damage by 1d10 plus your Dexterity modifier plus your Monk level, and then, if that reduces the attack to zero, you can spend a DP to turn it back on the attacker or another foe.

But, setting aside this limited means of outputting damage, how does this compare in terms of defense?

As is usually the case, it seriously depends on the nature of the battle you're in, the luck of the rolls, and other factors.

But get a sense, I want to try a scenario in each tier. I'm going to set Barbarians aside and instead look at a Paladin as a point of comparison, because many other classes can similarly get high ACs with medium or heavy armor.

To begin, we'll look at a tier 1 encounter in which a single Orc is attacking a 3rd level (this is the level this comes online) hero. The "Orc" stat block is a little tougher than your garden variety goblins. We'll assume, because of this, that there aren't a ton of foes in this fight. This one orc is the only one that's really going after our hero (who, to be clear, could be an orc themselves). To compare the relative survivability, we want to see, on average, how many attacks it takes to put a hero down.

We'll also assume the following: both characters have a +2 to Constitution, are taking average HP at each level up, and have started with the Standard Array. Our Paladin is wearing chain mail and a shield (not having gotten enough gold to upgrade to split yet) and our Monk has a +3 to Dex and a +2 to Wisdom. In other words, we're looking at the following key defensive stats:

Paladin: 28 HP, AC 18

Monk: 24 HP, AC 15

No one has gotten any serious magic items that can increase defensive stats yet.

An Orc can make a single Greataxe attack as an action, with a +5 to hit and dealing 1d12+3 slashing damage, or 9.5 on a hit and 16 on a crit. (I'll note here that the lack of multiattack favors the Monk - this might change in higher tiers).

Attacking the Paladin, the Orc is going to hit on a roll of 13-19 (35%) and crit on a 20 (5%).

So, per attack, we're looking at 35% of 9.5, which is 3.325, and 5% of 16, or .8, giving us a total damage per round of 4.125.

With 28 HP, it'll take this Orc an average of 6.79 turns to take down our paladin - not bad, honestly, as it's unlikely he'll live long enough to do so.

Attacking the Monk, the orc only needs to roll a 10 to hit, so it'll hit on a roll of 10-19, or 50%, and again crit on a 20.

Per attack, we have half (50%) of 9.5, or 4.75, and then our same .8 from the crits, for a total of 5.55 damage.

But, then we apply the Monk's deflect attacks, which at this level is 1d10+6, and thus equal, on average, to 11.5.

Meaning that, most of the time, the Monk is going to fully negate the attacks and could theoretically live forever.

    (Note: I made a slight error - they'll only be deflecting when there's a full hit, which means that actually landing the hit gives an average of 9.5, or a crit doing 16. It's less likely that the Monk will fully negate a crit, though they will significantly reduce it. However, more often than not, they will fully negate hits.)

Naturally, this is where taking averages fails us - sometimes, the Orc is going to roll high on their damage dice and/or the Monk is going to roll low on their deflect attack die. I will say, though, that given that the minimum reduction is 7, that means the Orc is going to need a minimum of 4 on their damage die - they have a 75% chance of doing so, but it is a pretty hefty chunk out of the damage.

    But let's skip ahead. In fact, rather than going to tier 2, we'll go to tier 3. And we'll go with a much newer monster. A monster I, in fact, used just last night on my newly tier 4 party. While these guys are a serious threat in large numbers against a tier 4 group, a tier 3, perhaps level 13 group, might face off against one or two of these guys: Ferrumach Rilmani. (The Rilmani are the true neutral to the Outlands - I reskinned them as non-evil but angry spirits of the dead within the Ghost Quarter of Agryem on Ravnica, which I've imagined as a sort of surreal underworld/Shadowfell for Ravnica, and where the dead spirits are not undead, because they're where they're supposed to be, and are thus generally considered celestials).

A Ferrumach has three attacks that have a +8 to hit and deal 1d10 slashing damage and 2d10 psychic damage. We'll assume here that there's no resistance to psychic or slashing, so it all comes out as just normal damage (by level 13 as well, a Monk's Deflect Attacks can also deflect psychic damage, so it will be fully effective against these attacks).

Now, my prediction here is that the thing that will hurt the Monk is the many attacks - even if they can do a massive amount of damage reduction to a single attack, that won't carry over to the damage of the other attacks.

At this stage, I think it's reasonable to assume that a Paladin would be in full plate, but perhaps not any kind of magical armor. Our Monk has had three chances for a feat (apart from the 1st level feats). While I think the design of the new 4th level feats (all giving a +1 to one of your stats) means that many more builds will go for them, I'm going to keep this simple and assume the Monk has gone in for pure ASIs to bump up their Dexterity and Wisdom. And while I think a Paladin has good reason to consider upping their Constitution, they could also go with Charisma to buff their Aura of Protection and their spells. So each character will still have a +2 to Constitution. The Paladin has gotten their Strength to +5 and Charisma to +3, but that's not relevant to their melee survival. The Monk, however, having gotten to +5 in Dexterity and upped Wisdom to +3 now has an AC of 18 (I don't think it's outside the realm of possibility for them to get Bracers of Defense, but we'll say the DM has been very stingy with magic items). So, let's look at their stats:

Paladin: 108 HP, 20 AC

Monk: 94 HP, 18 AC

Our Ferrumach has a +8 to hit and deals a total of 20.5 average damage on a hit with their Sharpened Limb, and deals 37 damage on a crit on average.

Attacking the Paladin, the Ferrumach has to roll a 12 or higher to hit, so gets a hit on a roll of 12-19 (40%) and crits on 20 (5%). So, per attack that's 8.2 plus 1.85, or a total of 10.05 damage per attack. With three attacks, that's 30.15 damage per round. Thus, it'll take 3.59 rounds on average for the Ferrumach to take down our Paladin.

Attacking the Monk, once again they only need to roll a 10 to hit, so they have a 50% chance to get a hit and a 5% to crit. That means each attack will do, on average, 10.25 plus 1.85, or 11.1 damage per attack.

However, our Monk can deflect one of those attacks. At this level, their deflection is 1d10+18, or 23.5. Again, this means that there's a good chance that they'll fully deflect one of these attacks. Given how close the average deflection is to the average damage, it's probably going to let in a little bit half of the time, but it'll always be taking a big chunk out of it.

Still, for the sake of argument, we'll imagine that the "average turn" sees the deflection negating an entire attack. The others incorporate the miss chance into them (hey, can you tell I'm not a statistician?) so we'll basically be counting two attacks as working as normal. That means the Monk is taking an average of 22.2 damage per round.

And thus, it's now taking the Ferrumach 4.23 rounds to take the Monk down.

    So, I've got to say, I was worried a bit about the Monk's ability to be a front-line fighter. But in terms of survivability, this seems pretty damn respectable. Naturally, this does cost the Monk their reaction, which limits things like Slow Fall and opportunity attacks. We're also ignoring a ton of other features that could come into play.

But in terms of just being able to stand up to a Monster and take a beating, Deflect Attacks has become a real game-changer. Without it, the Monk is obviously not going to be able to stand up to as much. But with it, they're arguably better at tanking than most.

Again, against a monster with a ton of attacks - something like a Marilith, for example - you're going to see the value of Deflect Attacks depreciate. Likewise, a Monk doesn't want to get swarmed. I can't recall off the top of my head what the hardest-hitting attack in the game is. It might belong to the Aspect of Bahumut's Bite attack, which deals 2d12+10 piercing and 4d10 force, for a total of 45 damage on average. A 20th level Monk deflecting that attack (and assuming the new Monk capstone) would be rolling 1d10+28 when deflecting, which averages out to 33.5. That means it's probably not usually going to be fully negating that attack, but will take a major chunk out of it most of the time.

Once again, I don't have the mathematical proficiency to really determine if this is going to ultimately mean Monks are the tougher front-liners. I also think it's always going to be hard to beat the Barbarian's fully halving of most melee damage they take (though we'll have to see if they keep giving high-level monsters force damage on their attacks, which would negate this advantage) combined with their massive health pools.

Still, Deflect Attacks is really good. Probably doesn't need any improvements before it goes to print.

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