5E Flames of Phlegethos Racial Feat Guide

Harkening back on infernal ancestry, a Tiefling mage draws on the history of their blood to make their fire especially potent and powerful, the Flames of Phlegethos feat powering up their attack and finishing with a wreath of fire lighting up the dark cave around the party, making it possible for even the human adventurers to see and identify targets in the dark caves as the battle raged in the caverns.

The Flames of Phlegethos (say that 5 times fast) are another racial feat that do what the best racial feats in Xanathar’s do: provide a very niche application to the classes most likely to take the feat with a wonderful flair that lives up to that idea of “diving deeply into the traditional lineage/bloodlines” of the race.

The Flames of Phlegethos feat is a Tiefling-only racial half feat in 5E DnD that gives a +1 to INT or CHR ability score boost, allows re-rolling 1’s on spell-based fire damage, and gives a well-lit “mini-shield” of flames that reacts to enemy’s melee attacks.

This is a very niche feat. It’s not one that is going to bowl over players or even work for most Tiefling casters, but if you want to be all about the fire mage build it can be a fantastic addition to your build. Let’s dive in!

tiefling fire mage
You want a Tiefling fire mage? I’ll show you how this feat makes you a Tiefling fire mage! Great picture originally found here.

Breaking Down the Flames of Phlegethos Racial Feat

Let’s break down the benefits of the Flames of Phlegethos feat and the very specific character build that it was clearly built for.

Directly from Xanathar’s Guide to Everything:

Prerequisite: Tiefling

You learn to call on hellfire to serve your commands. You gain the following benefts:

  • Increase your Intelligence or Charisma score by 1, to a maximum of 20.
  • When you roll damage for a spell you cast, you can reroll any roll of 1 on the fire damage dice, but you must use the new roll, even if it is another 1.
  • Whenever you cast a spell that deals fire damage, you can cause flames to wreathe you until the end of your next turn. The flames don’t harm you or your possessions, and they shed bright light out to 30 feet and dim light for an additional 30 feet. While the flames are present, any creature within 5 feet of you that hits you with a melee attack takes 1d4 fire damage.

Xanathar’s Guide to Everything, p. 74

That’s a lot to chew on for a new D&D player, so let’s break down those feat benefits one by one in-depth to get a better sense of what this feat really brings to the table.

Benefit #1: Increase your intelligence or charisma score by 1, to a maximum of 20.

My first thought was “Fire Mage Build” which means wizards or sorcerers at first glance and it seems like the designers at Wizards of the Coast seem to be thinking the same thing. I’m not generally big on half-feats, but this isn’t bad.

Intelligence or Charisma covers most of the main casting classes, and it especially focuses on wizards and sorcerers, the two classes most likely to go with a fire magic heavy build, making it a targeted if not unconventional pair of ability score improvements.

Benefit #2: When rolling fire damage from a fire spell you cast, you can reroll any 1, but must use the new roll (even if it’s also a 1).

If you have a terrible fireball full of 1’s, the relief of the DM will be short-lived as you get to re-roll all those ones. That’s a fairly powerful boost although it won’t always be in play as this means it will generally be a 1 in 6 or 1 in 8 chance of actually coming up per die.

Benefit #3: You can choose to be wreathed in flames after casting a spell that does fire damage, which sheds bright light for 30 feet and dim light for another 30, while any creatures hitting you with a melee attack within 5 feet take 1d4 fire damage.

Thematically amazing, very interesting/intriguing, but probably not overly powerful. 1d4 fire damage isn’t much but every little bit can help and that extra light can help when ambushed in a cave for those in the party who only have dim vision or no dark/dim vision at all, but it also lights you up as a target for anything in the darkness.

How Good Is Flames of Phlegethos?

While Flames of Phelgethos isn’t going to knock your socks off by any stretch, a half feat that basically adds the Savage Attacker feat to fire-based spell damage and the ability to bring light to the darkness with a watered down fiery version of Armor of Agathys is a pretty neat combo that thematically is definitely on point for your traditional Tiefling fire mage build.

This racial feat is meant to serve a very specific purpose and build. In that, it’s a good feat. It’s a fairly solid addition even to not a pure fire mage, but not necessarily enough to beat out other available feats.

This is sort of the definition of a C+ overall, B conditional feat.


  • The ability score improvements are aimed at the casting classes most likely to take this feat
  • Can save a terrible fire damage roll
  • Extra damage off a 1 is always a good thing
  • Small amount of protection and light in caves can be useful for low level adventurers


  • Nothing overpowering or overwhelming
  • Very narrow focus
  • If you don’t roll any 1’s, none of the damage bonuses kick in

Who Should Take Flames of Phlegethos?

  • Tiefling flame sorcerer or flame wizard builds

Basically what anyone in the RPG space would traditionally refer to as a “Fire Mage.” If your Tiefling is all about the flames and fire (and kudos to going old school on that DnD build!) then this is the racial feat that is built to pretty much do just that.

From a flavor standpoint it makes sense that the ultimate flame mage would be a Tiefling with the infernal background and add the Dragonborn sorcerer subclass and you have a truly excellent build of a magic wielder truly mastering magical fire in 5th Edition. So if you love the fire mage build, then make this a part of your build along with the Tiefling class and enjoy being a master of all things flame.

Final Thoughts for 5E Flames of Phlegethos Feat

I like this feat, though I don’t love it. If you want to build a fire mage, then I do think this feat should absolutely part of your build from a Tiefling. This is a very specific feat that is meant for a hyper specific build. In that niche it works wonderfully well. Outside of it, it’s probably not worth passing on other available feats that 5E Tiefling casters would find useful.

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