I read this a while ago and started thinking of how to create the Ultimate Assassin. How about a Lightfoot Halfling taking 6 levels of the UA Underdark Scout Ranger, then 3 levels Assassin Rogue and finally 11 levels Battle Master Fighter?
DEX 16 (Increasing to 20)
Add 2 feats (Sharpshooter & Crossbow Master) and +4 to CHA through ability score improvements. If rolling stats instead, could add the Alert Feat instead of a bump to DEX.
Racial bonuses include the ability to reroll 1's on a d20, move through spaces of larger creatures and hide behind them.
Through the Underdark Scout, you'd have Advantage on Initiative, Archery Fighting Style, +4 to damage on Favored and Greater Favored enemies, +10 bonus to speed and an Extra Attack on 1st round of attacks, Dark vision and the ability to hide from creatures with darkvision, plus a few spells & other Ranger stuff.
Through Assassin you get 2d6 Sneak Attack + Advantage on attack rolls & critical hits on surprised opponents on 1st round through Assassinate.
Finally, Battle Master gives you another Fighting Style (+1 to AC via Defense), Second Wind, Action Surge, 7 Manuvers (Precision & Menacing Attacks are a must) with 5d10 superiority dice,
So, if you roll a higher initiative (with advantage) and surprise an opponent, you should be able to attack them with a crossbow 5 times (3 attacks via Battle Master, 1 via Underdark Scout -1st round only- and 1 via Action Surge). Using Sharpshooter (and Precision Attack if needed) you should land all 5 attacks. Assuming you landed all 5 without the need for Precision Attack, your damage would be:
5d6 (Crossbow) + 25 (DEX) + 20 (Favored Enemy) + 50 (Sharpshooter) + 5d10 (Menacing Attack) + 2d6 (Sneak Attack).
That should add to an average of 146 points of damage.
You can add an additional 5d6 + 5d10 + 2d6 if the enemy is surprised or an average additional 51 points of damage.
I am starting now a campaign with an half-drow assassin 3/ fighter 2 and I am planning to get at least two level of Warlock in order to be able to use the darkness granted by the race with devil's sight, pact blade and hex. what I am unsure about is if i would also benefit from other levels as an assassin or fighter (then probably battlemaster) or just go warlock from now on...
The deadliest and most true to form Assassin is still actually the Rogue Assassin 17/Fighter Battle Master 3. Mechanically this build does the most nova damage and stylistically it’s in a way that’s simple and elegant....