Stacking extra attack

[Dr.Samurai]

I mean obviously barb is a uniquely terrible candidate to go caster with (frankly, this is a not-insignificant factor in barbs being arguably the worst class).

Eww... keep your stinking spells away from my barbarians thank you very much.

Paladin isn't a bad pick for them though; smites are still usable when raging, as are all of the other paladin tools besides spells. And I would definitely be eyeing paladin if I had to start barb and knew I was going to 15 or higher.

I'm currently running a barb/paladin (level 14). Went through Descent into Avernus and now we're doing Chains of Asmodeus. Great combo. Get it while you can; 1D&D has changed smites to spells so anyone that switches over won't be able to benefit from this going forward.

[Psyren]

While Rage won't work with Smite going forward, Reckless Attack still does; that's the main thing I'd be getting from the combo personally. Paladins can even counteract the drawback, e.g. Protection from Evil.

Now, the above system does not work that well in 5e; resource allocation is different. In AD&D, your additional WPs are a resource in and of themselves. In 5e, your ASIs are more limited, and spending them on feats means you're not spending them on ASI. Some of the AD&D martial arts manuevers are class abilities in 5e; "Ironskin", the Physical Training ability, isn't too far from the Barbarian's ability to use their Con bonus on their AC. You can somewhat mimic others if you take every ASI as some sort of weapon or combat feat, like Martial Adept giving you special maneuvers you can pull off, but that then put the martial types behind their caster counterparts in another way... the casters are all sporting 20s, while the martials capped at 17, spending their ASIs on things that don't give stat bonuses... which is rough, since they're already more MAD than casters (martials NEED constitution, since their job is to take the punches; casters LIKE constitution, because it gives more HP.)

Fighters *do* somewhat address this, by sneaking in a couple extra ASIs. But the consistent complaint that martials significantly lag in T3-T4 means, to me, that it needs to be addressed further. Thus, kung fu powers.

Note that you can give extra feats to your martials in lieu of treasure if you want (DMG 231). I actually like that better as a reward structure than dumping gold on the party when there's nothing to really buy, or flooding them with magic items that don't fit the the setting theme.

Note that ASI itself is becoming a feat this year, so MAD players will likely appreciate such a reward even more!