If a clause was added to Beast Master Rangers to allow them to spend a bonus action to have their companion to make a single attack after the ranger makes their own Attack action, what would the negative ramifications be?
My goal is to make the Beast Master (PHB, p. 93) on-par with the Xanathar's additions, which an overall consensus from the community is fairly clear that it is not.
Mechanically, I want this modification to play very similarly to dual wielding in terms of use, but I know that this does heavily change Beast Masters, and modifying the action economy without an expendable resource is a big deal.
Would this create a problem with Beast Master Rangers becoming too effective?
Best Answer
This is not overpowered and works fine
I have personally run for a Ranger PC who went with Beastmaster, and as the DM I ruled this very thing; the animal companion can act on the Ranger's turn as a bonus action rather than an action. It worked well and it didn't make the Ranger seem overpowered compared to the other PCs.
It allows the Ranger to still attack on their turn, but also allows the animal to do something as well, rather than one of them seeming useless. It does still have a cost, so if the Ranger wants to cast Hunter's Mark, they need to not have the animal attack that turn, or if the Ranger is a dual wielder, then they've still got to choose between their off-hand attack or the animal (in my case, the PC was an archer, so this didn't come up).
Indeed, compared to a Ranger who is dual wielding, there's little mechanical difference, since there's still 2 attacks being made (or 3 once the Ranger has Extra Attack at level 5). If compared to the Hunter archetype, with class features like Break the Horde, they get to make 2 attacks (or 3 with Extra Attack at level 5) with just their action, so they still get to use Hunter's Mark as well, all in one turn.
Like I said, this houserule for Beastmaster Rangers is exactly what I ruled when I was for a Ranger PC, and it seemed well balanced to me and the players, and this was all the way from 3rd level to something like 9th I think before that character met their end...