Does Flames of Phlegethos interact with Elemental Adept if you rerolled a 1?

Question

Flames of Phlegethos (a feat for Tieflings from UA, later published in Xanathar's Guide to Everything) has this ability:

When you roll fire 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.

If you ended up with a 1, can you then apply this benefit of the Elemental Adept feat (PHB, p. 166) to it?

...when you roll damage for a spell you cast that deals damage of that type, you can treat any 1 on a damage die as a 2

You are still using the rerolled 1, you're just treating it as a 2?

Answer 1

Yes, these Feats work together

If you have chosen the feat Elemental Adept and picked Fire, then you can turn a 1 into 2 every time.

This investment in two Feats basically gives you a lower limit of 2 on any fire damage die and you can still use the Feat Flames of Phlegethos prior to that to try and increase the damage beyond that.

Answer 2

They work together just fine! Here's the order of how things would work.

1. Basic roll, result 1.
2. Reroll for Flames of Phlegethos. Result still a 1.
3. Elemental Adapt turns it into a 2.

The end result is that you're more likely to get higher damage, but have a lower limit of 2 on any die you roll for fire spell damage.