So I keep seeing this mentioned, and personally... I'm a fan, its way cleaner than the reroll 1s and 2s, at least, to me. Its very simple. But, I wanted to see how the math plays out on it before I just declare it the way I go.

So to those who are anti-math in their house rules, welp, just ignore the rest of the post. To those who are curious, keep reading.

First, I looked at two handed weapons. They fit into three different damage groups. I'm going to call it Pikes (1d10), Greataxe (1d12) and Greatsword (2d6).

And then I decided to check out what changing the rule did for each damage type. First up, Pikes.



The original rule increased your average damage by 0.80. Rolling twice keeping the highest on the other hand gives you a boost to average damage of 1.65. Nearly twice as much. But I want to look at the other weapons before I make a decision on if this is bad. So on to Axes.



Original rule: +0.83. Rolling twice: +1.99. An even bigger increase. It would seem this rule is a bit much, but its really hard to make a true assessment without looking at what it does for the greatsword.



... Its just really cool how close the new rule and old rule lines are. Its so cool. The difference in expected damage between the old and new rules is about 0.04, pretty much unnoticeable.

Here is the opinion on it. I think its perfectly fine. Yes, it gives more of a boost to the greataxe and pike, but because of how the original rule interacted with the greatsword, mathematically it was always the best choice (though reach can change that). With the new rule, the Greataxe and Greatsword do comparable damage for a great weapon fighter, and the pike with reach becomes a nice alternate choice, rather than doing nearly 2 points less than the Greatsword.

One thing you may want to take into account.

And this is odd, but it seems the intent of the rule is to allow you to re-roll all damage dice on a 1 or a 2, not just the one from the weapon. So if you have 2d6 Martial Advantage damage because your a hobgoblin fighter pc with a voluge, you get to re-roll them too. As you would if you got a greatsword that did 2d6 fire damage.

I proimice I am not bringing this up just cos I like seeing more graphs....

Well, at current, there isn't any two handed finesse weapons, so rogue sneak attack damage couldn't be combined with great weapon fighting. But just in case, we can look at a graph of what rerolling the whole damage roll would do to the extra damage:



Overall, the numbers stay close together. Interestingly, the more dice you roll, the better rerolling 1s/2s gets, and the worse best of two becomes. But it is never a big enough difference to matter.

And if you are rolling an insane amount of d6, more power to you, you probably don't need the bonus damage near as much.

As a note, there is a mistake in the original chart for greatswords. The correct reroll 1s/2s is in the sneak attack chart at 2d6.