Except booming blade doesn't prevent anyone from moving... but let's get back on topic.
Does anyone feel like explaining to me how you guys come up with the damage per round calculations? What's assumed based on chance to hit, etc. Or just point me to a thread that already explains this.
Sent from my SM-G955U using
EN World mobile app
I'm replying without having read other replies. So if I duplicate any responses consider it reinforcement of their point.
I start with average damage per hit. The damage per hit is subdivided if there are different sources of damage that don't always land together. For example, a Ranger 5/Rogue 3 with dex of 18, a rapier, colossus strike, hunter's mark and sneak attack. He's got two attacks but colossus strike and sneak attack can only hit once.
So (using Excel, because it's awesome) I have something that looks like this:
weapon: 1d8+4 8.5
colossus strike: 1d8 4.5
hunter's mark: 1d6 3.5
sneak attack: 2d6 7
I then assume a hit percentage. To keep my sanity, I assume a base 65% chance modified by whether your attack stat has kept up with your ASIs. That is, I expect 16 from levels 1-3, 18 from levels 4-7, and 20 from levels 8+. I adjust hit chance based on the above so in my example the PC has a 60% hit chance. If, for example, you are a level 6 fighter who has a 20 stat you are "ahead of the curve" and I assign a 70% chance to hit. 65% is basically correct given average monster AC.
When you get multiple chances to do one thing, the math is tricky. The weapon and hunter's mark are easy to calculate. But colossus strike and sneak attack can only land once. The easiest thing to do is calculate your chances of
not hitting once and then subtracting that from 1. In this case, .4*.4=0.16. Subtract that from 1, 1-.16=.84, and you get an 84% chance of sneak attack and colossus strike on your turn (assuming the target has less than max HP). If the target has max HP then you have to land with
both hits to get colossus strike, 0.60*0.60=0.36.
If the target is below max HP and you can get sneak attack, you can combine the weapon and hunter's mark damage (12.0) and also the colossus strike and sneak attack damage (11.5). And you end up with something like this:
12.0*2*0.60+11.5*.84=24.06
Oh, but you're not done yet! You have to calculate critical hit damage. For the regular attack and hunter's mark, it's easy. It's 0.05*2*8 (where 8 is the average of the dice you'd roll on the crit) =0.80.
The sneak attack and colossus strike are a bit trickier. If you hit on the first attack, you'll likely apply colossus strike and sneak attack (you might not if the target has low hp and will die, but I've never seen anyone but me do anything other than assume targets have infinite hp). If you do that, it doesn't matter what happens on the second attack. Therefore, you have a 0.05 chance of getting a crit with sneak/colossus on the first attack and you'll only have an opportunity to get a crit on the second attack if you miss on the first one. So that's 0.40*0.05=0.02 or a 0.05+0.02=0.07 chance total.
The math for that is 0.07*11.5 = 0.805.
All told we have 24.06+0.80+0.805=25.665 DPR.
If the creature is at max HP (so no colossus strike on first attack) the math is 12.0*2*0.60+7.0*0.84+4.5*0.36+8*2+0.05+7*0.07+4.5*0.03=23.325 DPR.
As you can see, things get messy really fast.
EDIT: If you want to assume a different hit chance or advantage, it's really easy as all I (or you) have to do is plug a different number into your 'hit' and 'crit' block on the spreadsheet and it'll auto-calculate any change.
In fact, if you calculate each damage source separately it's easy to calculate damage per round with, say, assuming you can't get sneak attack in. It's not really hard. The key is to start by separating out all the bits.