How does the Oathbow’s benefit to ranged attacks interact with the Arcane Archer fighter’s Arcane Shot options Piercing/Seeking Arrow?


Part of the description of the oathbow magic item says:

When you make a ranged attack roll with this weapon against your sworn enemy, you have advantage on the roll. In addition, your target gains no benefit from cover, other than total cover, and you suffer no disadvantage due to long range. If the attack hits, your sworn enemy takes an extra 3d6 piercing damage.

However, the Arcane Archer fighter archetype from Xanathar’s Guide to Everything (previously appearing in UA: Revised Subclasses) has the ability to imbue their arrows with magic. Two of the Arcane Shot options seem like they might conflict with the oathbow‘s trigger condition.

The description of Piercing Arrow says, in part (XGtE, p. 29; identical to the version from UA:RS):

[…] When you use this option, you don’t make an attack roll for the attack. Instead, the arrow shoots forward in a line, which is 1 foot wide and 30 feet long, before disappearing. […] Each creature in that line must make a Dexterity saving throw. On a failed save, a creature takes damage as if it were hit by the arrow, plus an extra 1d6 piercing damage. On a successful save, a target takes half as much damage.

The description of Seeking Arrow similarly says (XGtE, p. 30; also identical to the UA:RS version):

[…] When you use this option, you don’t make an attack roll for the attack. Instead, choose one creature you have seen in the past minute. The arrow flies toward that creature, moving around corners if necessary and ignoring three-quarters cover and half cover. If the target is within the weapon’s range and there is a path large enough for the arrow to travel to the target, the target must make a Dexterity saving throw. […] On a failed save, the target takes damage as if it were hit by the arrow, plus an extra 1d6 force damage, and you learn the target’s current location. On a successful save, the target takes half as much damage, and you don’t learn its location.

So how does the oathbow interact with these 2 Arcane Shot options by RAW?

I know some situations override things going both ways in favor of exploitation and prevention.

Does the class skill let you bypass the attack roll while getting the oathbow‘s power buff? Or do you not get the buff?