Another Demihuman Subclass

 Haven't played for a couple weeks now, we're avoiding congregating while the pandemic rages. Missing it. Picked up Tasha's Cauldron of Everything, excited to try out a couple of the subclasses at some point. I think I want to start with the Star Druid, I've been thinking a bunch about the build, think it might be an interesting fit for a Protector Aasimar. 

Also reading on and off still Moore's Demihumans of the Realms. Just got to Hound Master, which made me think it could be interesting to rework the Ranger Beastmaster into a Fighter subclass. I know people (myself included) tend to disparage the Beastmaster, as the beast companion rapidly becomes less effectual as characters increase in overall power, pretty much from tier 2 onward. And the Ranger class itself, when you strip out the subclass abilities, also leaves something to be desired, particularly compared to some of the good stuff built into the Fighter like second wind, action surge, extra extra attacks, and bonus feats. 

Ideas for a Houndmaster Fighter Martial Archetype

The first domesticated animal for both humans and demihumans on most worlds is the dog, derived from the wolves who joined humans in a partnership of mutual benefit long, long ago. Most demihuman and humanoid cultures have some form of partnership with canine companions. The Houndmaster is a warrior who forms an especially strong bond with these animals.

 Canine Companion

When the fighter takes this archetype at 3rd level, they gain the animal handling skill, or another skill from the fighter or ranger skill lists if they already have it. The fighter also gains the benefits of the Ranger's Companion ability, with the exception that the beast companion is limited to the options of mastiff, wolf, and in the case of gnomish characters the giant weasel. Replacement of a lost companion is also changed, requiring expenditure of 25 GP and a day of downtime to locate a suitable replacement. 

Exceptional Training

Ability gained at 7th level. Identical to the 7th level Ranger Beastmaster ability. 

Packmaster

At 10th level, the character attracts additional companions. Three more beasts of the same type as the original companion join the Houndmaster's pack. These three additional beast companions use the standard version of the beast's stat block, but if the original companion dies one of the others immediately transforms and takes on the special characteristics of the original companion. When the Houndmaster uses an action or a bonus action to activate a beast companion, all four beasts can be commanded simultaneously to take either the same or a different allowable action. Replacement requirements for the additional companions are the same as for the original, given above. 

Bestial Fury

At 15th level, when commanded to take the attack action the Houndmaster's beast companions can make two attacks. 

Synchronized Movement

At 18th level, a verbal command or quick motion can suffice to order the Houndmaster's beast companions, who form part of a well synchronized team. An action or bonus action is no longer required to command the beasts to act, and they can take an action on the Houndmaster's initiative count, either right before or right after the Houndmaster himself acts. However, the extra attack from Bestial Fury still requires expenditure of one of the Houndmaster's attacks.

Final Thoughts

I think this might work, in my opinion the action economy isn't all that seriously disrupted if we just let one (or a handful even) of relatively weak creatures act somewhat more independently of the PC but I tried to stick close to the Ranger Beastmaster and only unlock the restrictions that annoy most players about the beast companions only at relatively high levels. Maybe multiple companions is a bit much, but by 10th level I don't think they break the game in any way, especially if the new ones are normal animals. A DM will probably want to adjust the allowable companions a bit to fit the cultural milieu of their game, but I think being more restrictive rather than less on beast choices here reinforces the Ranger as being more the master of the wild spaces, and being the one able to bond with weird and wacky creatures like flying snakes and giant crabs fits that concept better than the more prosaic fighter. But unlocking velociraptors for Lizardfolk or others living in the Dinosaur Swamp might be the sort of thing that makes sense for some campaigns.