2024 "Crit. fishing", potentially viable?

In 2014 the problem with critical hit fishing is that critical hits are generally too rare, or don't add enough damage to be worth it compared to other builds, but it seems like that might have changed slightly. Is crit. fishing viable now?

I will be focusing on Rogues to do some math for crit. fishing, but I think some non-Rogue builds might also be viable for crit. fishing tactics.

Looking at the Assassin Rogue, their level 3 feature was updated to grant Advantage on attacks in the first round of combat against creatures who have not had their turn yet, which you should see in play fairly often since Assassins now also get Advantage on Initiative starting at level 3, and with the Alert feat getting a feature to be able to swap initiative order with an ally, an Assassin Rogue should be able to go before at least one enemy close to 100% of the time.

With the updates to Two-weapon Fighting, and the new Nick Mastery, along with the updated Dual Wielder feat, a level 4+ Assassin Rogue with the Dual Wielder feat should be able to spend their Action, and Bonus Action to make 3 attacks in a round.

If 3 attacks are all at Advantage due to the level 3 Assassin subclass feature, or something else (like party members spamming the Topple mastery, or a Paladin using Shining Smite), each attack should have a 9.75% critical hit chance, so the chance that at least one of them will be a critical hit is about 26%. At level 4, a Rogue using a 1d6 weapon should get 3d6 (10.5 average) extra damage on a critical hit that includes Sneak Attack damage, which should amortize out to 2.625 average damage per round, or the equivalent of adding 1d4 damage (not including the non-critical hit damage increase of the extra attacks from Nick, and Dual Wielder). Technically any Rogue should be able to do this via the Nick Weapon mastery, and the Dual Wielder feat, but the Assassin feature to have Advantage on all attack in the first round means they will probably be able to do this more often than other subclasses.

Even without the Dual Wielder feat, or if you need to use your Bonus Action to gain Advantage on your first attack, as a Rogue you should be able to get about an 18.463% Critical hit chance across two attacks if you can start with Advantage on your first attack, while using the Vex master on that attack to get Advantage on a second attack via the Nick Mastery/Light Property. 18.463% should also be the critical hit chance of a crit. fishing single class Soul Knife Rogue making every attack, or at least most attacks, with Advantage due to their psychic blades having the Vex mastery, but not the Light property, or the Nick Mastery, which would only allows them to make 2 attacks per turn (a Soul Knife Rogue seems to either need to ignore their psychic blades entirely, or only use their psychic blade for the Bonus Action extra attack of the Dual Wielder feat in order to make 3 attacks per turn without a multiclass).

If you were to multiclass into Champion Fighter, to get a 10% critical hit chance normally, and a 19% critical hit chance when attacking with Advantage, this would give your 3 attacks a 27.1% chance of at least 1 critical hit when attacking normally, and if all 3 attacks have Advantage you would have a 46.8559% chance of at least 1 critical hit.

So an Assassin Rogue 4/Champion Fighter 3 build would get about an amortized 5 average damage from critical hits for rounds where every attack is with Advantage, and an amortized 2.5 average damage for rounds without Advantage that Sneak Attack can still be dealt.

For a damage comparison, going single class Rogue to level 7 would give you 2d6 more Sneak Attack damage per turn than a level 4 Rogue, and give 5d6 extra damage on a critical hit, for a DPR increase of 11.55 damage over a level 4 Rogue on turns with Advantage with every attack. Multiclassing Fighter should let you get the Two-Weapon Fighting Style feat, which adds Ability Modifier damage to the attacks of both Nick, and Dual Wielder, and should be adding an average of 5.16 damage to your DPR on turns without Advantage on every attack, with the damage from critical hits that would become 7.66 damage on turns without Advantage on every attack, if you have Advantage on every attack, that should be about a 12 damage increase over a level 4 Assassin Rogue, this is not including other benefits like Action Surge for reaction Sneak Attacks.

If you were to get Extra Attack from Fighter level 5, that would let you make 4 attacks per turn, for a 34.39% chance of a critical hit without Advantage, and a bit over a 56.95% chance of a critical hit with Advantage.

As a side note, if you use Action Surge to ready the Attack Action as a level 5+ Champion Fighter to get Off turn Sneak Attack, that should give a 34.39% chance of a critical hit across two attacks with Advantage. As an additional follow up, unlike the Cleave mastery which just specifies it can be used once per turn, allowing you to Action Surge to ready the Attack action, and get a second Cleave attack in that round, the Light property specifies "taking the Attack Action on your turn", so there should currently not be a RAW way to get a second Light/Nick attack per round. If your GM homebrews/rules that you can take the Ready action to prepare the Attack Action, and get a second attack from Light/Nick for the round, see above for the critical hit chances for crit. fishing with 3 attacks.

Going to extremes, if you go 20 levels of Assassin Rogue, and take the Irresistible Offense Epic Boon, you could create a character wielding two 1d6 weapons that will deal an average of 123 damage (118 damage in the "off-hand" attack from Nick, and Dual Wielder) on a critical hit that gets Sneak Attack damage in the first round of combat, which will happen on it's own about 26% of the time, along with a chance to double this damage if the target fails a Constitution save against the level 17 Assassin subclass feature. This character would deal an average of 103 damage (or 98 damage) on a critical hit that includes Sneak Attack damage in the 2nd round of combat onwards, and this is also the amount of critical hit damage that most non-Assassin level 20 Rogues should deal with a critical hit if they take the "Irresistible Offense" Epic Boon.

The level 20 Rogue feature would also let you turn a miss into a critical hit once per Short Rest or Long Rest, increasing the chance of getting a critical hit. If you are willing to spend Stroke of Luck to get a critical hit an attack with a 65% hit chance has basically a 40% chance of becoming a critical hit, if the attack had a 87.75% hit chance due to Advantage, that should be a 22% chance of becoming a critical hit, or 52.5448% chance of at least 1 critical hit across 3 attacks. As a level 20 Assassin Rogue you might want to consider using Alert to go lower down in the Initiative order, so that you could make 3 attacks without Advantage in the first round of combat, and have about a 78.4% chance at dealing a critical hit via being willing to expend Stroke of Luck.

Does this seem worth it?

Did I make any mistakes in the rules/math?

Are there any mechanics I am missing, or that people would want to highlight?

I focused on crit. fishing with Rogues, and the Rogue/Champion Fighter multiclass, are there other classes, subclasses, or multiclass combinations that should be highlighted for 2024 crit. fishing?