I believe Wolfheart during one of his streams recently said that abilities that Minthara uses in combat are abilities from the Oath of vengeance subclass, but he can be wrong of course and Oathbreaker may have the same abilities. It is interesting if Oath of vengeance paladins will have the same criteria to break their oath as others.
Oathbreaker use Oathbreaker DMG abilities and spells list.
And after reading your post, I went to check (abusing tadpole powers to avoid fights) and Minthara is indeed Vengeance. She used Vow of Enmity and Hold Person. Oathbreaker doesn't have either.
Why didn't they make Vengeance available to us???
