Horwath
Legend
But does it need fixing?
I mean automatic criticals is insanely strong, especially on a class like the Rogue, who is doubling their already huge spike damage. There is no other feature in the game that grants that ability.
Bearing in mind at 3rd level the Assassin is also getting advantage to attack rolls against creatures that have yet to take a turn (every single combat) - another strong ability - and 2 tool proficiencies as well, isnt it totally appropriate and balanced that the 'auto-crit' feature only ever triggers pretty rarely, AND takes a bit of effort (and luck) to set it up to work in the first place?
I mean by comparison, at the same level (3rd) Thief rogues can climb and jump a bit better, and gain the ability to interact with an object or pick pockets as a bonus action. Swashbucklers gain a bonus to initiative, slightly easier sneak attack, and half the mobility feat. Scout Rogues get a reaction half move every turn, and 2 bonus proficiency.
It seems totally balanced compared to those features, and even then only when you take into account it will only happen relatively rarely.
problem is that with RAW it takes too much effort and too much luck:
1. You must ditch everyone from your escort(party) that cannot sneak as good as your or as closely good as you. And even if they can...more people, more chance that someone will fumble their stealth check.
2. You must be in terrain that gives opportunity for stealth. Most of the time you will get this chance. Unless DM likes his battlegrounds in open field or town squares in high noon.
3. You need to win your stealth check.
4. You need to win initiative
5. You need to hit. Even with advantage misses happen.
So, you need all that passed so you can, sometimes, on 3rd level, get an extra 3d6 damage? Once per battle.
When you remove bullet point 1&4, it is a good ability, with those it is too circumstantial.