If you use the "Steady Aim" feature from Tasha's, then Rogues will have advantage whenever they want, as long as they are willing to have a Speed of zero. This is what makes the L7 Half Elf Rogue with Elven Accuracy a kill-bot in the game I am running.I’d also note that it leaves a little more room mechanically for rogues to either do something else cool on a crit, or to have a limited use ability to nova that is more in the player’s hands.
The rule by itself does frankly need the already wonky assassin into the dirt. Even if you play exactly as an assassin needs to get the most out of its subclass, you will barely be doing more damage than any other rogue. In fact, a swashbuckler with mage slayer or sentinel probably does more damage.
Definitely a fixable problem, but it does mean I won’t be making any assassin rogues for playtesting until there is a playtest rogue!
I’d love it if rogues get a “when you crit, the attack can deal sneak attack damage even if the attack didn’t qualify for it” and in tier 2, “when you crit, choose from one of these [3, 4 at most] effects”, one of which is to move a short distance and hide or make an attack, another of which might be to slow the target if it survives, and another could simply be some sort of damage buff.
At tier 3 at latest, IMO rogues should add “make a single weapon attack” to cunning action. Maybe combine this with crit effects, and make one of the options just “use cunning action without using your bonus action”.
I’m glad I read this post now, before running my first playtest session for this UA.
Yeah tbh I always encouraged only smiting on a crit, because IME it meant Paladin players used spell slots more out of combat, but this might get us there even better.
I’ll also say, I think if the cleric is going to have access to all divine spells, I think the Paladin should get some benefit when they hit with an attack that deals extra damage from a spell they cast, like adding their Cha to the damage or something. Paladins should be the best at smiting, even when it’s via spells others can also cast, IMO.