There are two ranger archetypes in the PHB; the Hunter and the Beastmaster. There are three ranger archetypes in Xanathar's Guide to Everything; the Gloom Stalker, Horizon Walker and Monster Slayer. These three learn some free spells via class features such as Gloom Stalker Magic, etc. Quoting this example (although the similar features from the other XGTE archetypes say much the same thing):
Gloom Stalker Magic
Starting at 3rd level, you learn an additional spell when you reach certain levels in this class, as shown in the Gloom Stalker Spells table. The spell counts as a ranger spell for you, but it doesn't count against the number of ranger spells you know. (XGTE, pg. 42)
Essentially, they learn a free 1st-5th level spell as they gain access to spells of that level. The Hunter and the Beastmaster do not.
Given how few spells rangers learn anyway, Hunters and Beastmasters now have even fewer retrospectively. Even the Primeval Guardian archetype from UA learns free spells. So I decided that these two ranger archetypes should also learn free spells to bring them into line with the other ranger archetypes.
In other words, I want to invent new "Hunter Magic" and "Beastmaster Magic" class features, exactly the same as Gloom Stalker Magic, but with different spells that suit the Hunter's and Beastmaster's theme better.
I'm sure others have done something similar, but for reference, here are the spells I picked that I felt matched their flavour (in case my exact spell choices impact the answers):
- 1st: Hunter's Mark
- 2nd: Hold Person
- 3rd: Slow
- 4th: Elemental Bane
- 5th: Hold Monster
- 1st: Animal Friendship
- 2nd: Beast Sense
- 3rd: Conjure Animals
- 4th: Dominate Beast
- 5th: Insect Plague
The Beastmaster ranger is infamous as being weak, so I imagine that answers to this question will focus mostly on the Hunter archetype (but who knows?), but does giving these PHB archetypes some free spells affect balance in a way that makes them stronger than the XGTE archetypes, or are they still competitive? In other words, would my players who were playing rangers think "Oh, I'll definitely go Hunter, now that it learns these extra spells" or is it still a pretty level playing field? Including against other classes, for that matter?
I personally don't think it would unbalance anything greatly, it's just a few extra spells known to a class that already has very few, and if it's alright for the XGTE ranger archetypes, I imagine it'll be fine here, but I might be underestimating the strength of the existing class features of the Hunter archetype, or overlooking something else entirely.
Adding the spells to the PHB Rangers will be fine
For this, I will compare the simplest existing examples from both books, the Hunter from the PHB and the Horizon Walker from XGtE.
We'll compare how strong each one is overall, and decide if the update is warranted.
For every circumstance the Horizon Walker is superior, the overall suggestion gets a +1, +2 or +3. For every circumstance the Hunter is superior, your suggestion gets a -1, -2, or -3. If neither is superior, then the result for that comparison is 0.
If the final result totals to 0, then the classes are already balanced against each other.
Final Result: +3
Go for it. Even comparing the strongest of the two PHB classes, it definitely appears that the Horizon Walker is stronger in comparison, and the Horizon Walker is sometimes seen as the weaker of the 3 rangers from XGtE. All in all, your update should bring the PHB classes slightly more in line.