5e Reroll one die only (e.g. for Piercer feat)

[vonklaude]

I can add REROLL N to a weapon and it will reroll dice that roll N or below. The issue is that it will reroll all such dice. For example, on critting it will reroll both dice if they each meet the test.

However, in the 5e ruleset, the more standard case is that only a limited of dice are rolled - frequently one as with the piercer feat, or a small number of them as with empowered spell.

Is there a way to control the number of dice rolled? I guess the logic would be something like - REROLL N X - where the lowest up to X dice that meet the test of landing equal to or less than N are rerolled.

As a bonus, it would be great if there was a way to make an effect differentiate between increasing the damage dealt (sneak attack, favored foe), and doing additional damage (divine smite).

[Zacchaeus]

There's only reroll x; And it will as you say reroll all the affected dice.

There might be a way to do it using the dice roller https://fantasygroundsunity.atlassian.net/wiki/spaces/FGCP/pages/996640101/Rolling+Dice but none of that is built into any of the rulesets as yet.

Not sure what the difference between sneak attack and smite is - they both add extra or additional damage and both can be handled with effects right now.

[Lo Zeno]

As a bonus, it would be great if there was a way to make an effect differentiate between increasing the damage dealt (sneak attack, favored foe), and doing additional damage (divine smite).

You already can: when you deal additional damage, you can specify the type of additional damage you cause.
So for example if you create an effect like `DMG: 2d8 radiant,melee` it will do additional radiant damage on top of the normal weapon's damage (which could be 1d8 bludgeoning for example).

With Sneak Attack, instead, you'd create an effect like `DMG: 1d6` and it would add 1d6 damages of the same type as the weapon (thus increasing the damage dealt)