What total is the Unearthed Arcana Fighter Brute's Brutish Durability feature referring to?

Question

On 2018-01-08, three new subclasses were released as Unearthed Arcana material. Of those 3, there is the Brute, a Fighter's archetype. At level 7, a Brute gains access to the following feature:

Brutish Durability

Beginning at 7th level, your toughness allows you to shrug off assaults that would devastate others.

Whenever you make a saving throw, roll 1d6 and add the die to your saving throw total. If applying this bonus to a death saving throw increases the total to 20 or higher, you gain the benefits of rolling a 20 on the d20.

Emphasis mine

So for example, rolling a 19 (d20) + 6 (d6) on your death saving throw would count as having rolled a natural 20, getting you back with 1 HP.

But what if the Brute had a friendly Paladin with a +3 aura near him? Or if he was equipped with a Cloak of Protection that grants +1 to all saves? Does this feature of checking if the roll is 20 or higher applies before or after those other bonus?

In other words, if a Brute were to roll 15 (d20) + 4 (d6) + 3 (Paladin's aura), would he gain the benefits of rolling a 20 for his Death Saving Throw?

Answer 1

It's ambiguous

AFAIK, there is no other modifier that does what Brutish Durability does for Death Saving Throws, so the intention is probably that the total needs to be increased to 20 or higher using this feature alone. However, as written, it can be combined with any other modifiers that apply.

I'm yet to work out in my mind if the many ambiguities in UA material are deliberate or accidental by WotC. It's possible that they are placed deliberately so they get feedback from people who have played it different ways. Its also possible that it's sloppy writing and they want us to act as their copy editor. Or maybe I'm just mistaking lethargy for strategy.