[RPG] the effect on a creature’s CR if it can choose to hit on a miss


We're playing a high-powered god-centric game where players are direct agents of gods of a pantheon I created. For the next session, I want to surprise them and throw in a couple of creatures (friendly and hostile) who are also agents of gods.

Anyway, I'm trying to make a creature with an uncanny ability to hit targets with an attack.

I'm basing it off of the DMG page 232:

Boon of Combat Prowess

When you miss with a melee weapon attack, you can choose to hit instead. Once you use this boon, you can't use it again until you finish a short rest.

Unfortunately, (correct me if I am wrong) there is no similar effect on any creature that exists in the Monster Manual, therefore this ability isn't listed in the Monster Features table in DMG 280.

I tried just increasing its DPR by a third of the total (since, assuming it survives 3 rounds, and has a 50% chance to hit, instead of 50% + 50% + 50% = 150%, it becomes 100% + 50% + 50% = 200%) to increase the creature's Offensive Challenge Rating. This turned out to be erroneous because after playtesting it, it became too easy to kill based on its CR and it didn't do as much as I had hoped it would, designing the playtest to be deadly, it didn't even kill a single PC.

So, if a creature can choose to hit on a miss, by how much would its Offensive Challenge Rating increase? If:

  1. The Creature's OCR is high because it has multiattack? (i.e. 1d6 x 2)
  2. The Creature's OCR is high because it has high damage dice? (i.e. 1d12)

Best Answer

I don't think it'd increase meaningfully

This is effectively having slightly better luck on one die roll. We don't increase monster CR because you manage to roll high a few times, yet effectively this is no better than a guaranteed high roll.

Unless one of the following is true, I would not change CR for the monster at all:

  • The monster has a high-damage, single-use ability that it will probably use this effect on. (In which case, change that ability to simply not require an attack roll and base CR on that)
  • The monster has extremely high damage, very low accuracy attacks (in which case, update that power to be usable only once and not require an attack roll and base CR on that)

Beyond that, it's not going to make a noticeable difference compared to what the luck of the dice is already doing.