The Restriction you're suggesting is a strict subset of the allowed rules in Adventurer's League Play

5th Edition Adventurer's League has a "PHB +1" rule for character creation, that requires that each character created for AL play be based only on materials found in

• The Player's Handbook, or


• One (1) additional officially published 5th Edition Sourcebook.

So your rule is a strict subset of that rule: of the officially published 5th Edition sourcebooks, you are only permitting Sword Coast Adventurer's Guide, for all characters. As such, while it's more restrictive than normal AL rules, it's definitely not absurd or unreasonable.

SCAG is probably a good pick for the restriction

Sword Coast Adventurer's Guide is unique compared to other Sourcebooks in that of the sourcebooks in the game, it focuses more on augmenting existing PHB material rather than providing whole new options wholecloth.

For example, unlike the other 5e sourcebooks, SCAG's only Racial options are variants on existing PHB races: Dwarves, Gnomes, Half-Elves, Halflings, and Tieflings

The only new spells SCAG offers are some (admittedly very powerful) melee-focused cantrips for Wizards, Warlocks, and Sorcerers

SCAG only introduces a small number of additional class archetypes, one each, for Barbarian, Cleric, Fighter, Monk, Paladin, Warlock, and Wizard. It also has two for Rogue and one for Sorcerer and one for Monk that were later reprinted in Xanathar's Guide to Everything.

And SCAG offers a fair number of new Background options, which were already customizable as-written in the PHB.

So if the goal is to keep character creation from getting overly complicated, limiting to the PHB and SCAG is a valid option.

Personal Experience: Allowing 5e sourcebooks, disallowing Unearthed Arcana or Homebrew, is pretty manageable for new players

The big "Expansion Sourcebook" in 5e is Xanathar's Guide to Everything, which contains multiple class archetypes for all of the 5th edition classes, has lots of new spells, has lots of new racial options, and also contains a lot of variant rules for DMs to use. So if you're worried about complexity, that's definitely the big one to watch out for; most of the other sourcebooks contain about as much player material as SCAG.

Having said that though, the options provided in Xanathar's (and the other 5th edition books) has been, in my experience, pretty manageable by players. The trick is assuring players that try to use any of these books that most of the material found in these books, even in Xanathar's, is flavor text that they don't need when creating their character (or at least they can ignore while they're trying to work out, mechanically, what they want to play). If you go through and enumerate/index each of the choices that are actually offered by each book, it'll make these choices easier for players.

That last point is important: it's a lot easier to figure out "what kind of Paladin do I want to be?" if you can choose from a specific list, i.e.

• Devotion (Player's Handbook)


• Ancients (Player's Handbook)


• Vengeance (Player's Handbook)


• Oathbreaker (Dungeon Master's Guide)


• Conquest (Xanathar's Guide to Everything)


• Redemption (Xanathar's Guide to Everything)


• Crown (Sword Coast Adventurer's Guide)

As opposed to trying to search through each book for the specific sections that describe each of those archetypes. If you put together lists like this for each class/racial option, your players will be a lot less overwhelmed by the choices they're being offered.

The one risk is background or class options that clash with your campaign: Guildmasters' Guide to Ravnica, for example, offers some Background options that are extremely enticing (especially for spellcasters), but which probably won't mesh well with any non-Ravnica based campaign. Other books have similar restrictions; SCAG, for example, offers the Bladesinger class to Wizards, which normally is restricted to elves and half-elves only. There's nothing stopping you, as DM, from lifting that restriction (and indeed, the text as seen in SCAG literally suggests lifting that restriction to suit the campaign if needed) but this is one more example of how you might need to tweak things or set ad-hoc rules on what players are or are not allowed to take.

So it's up to you. PHB + SCAG is definitely a reasonable restriction, but most newer players won't be too overwhelmed by allowing the other 5th edition sourcebooks as well, just plan to index the contents of Xanathar's Guide to Everything if you do decide to allow it, to make picking options out of it a little easier.

Let's flip the script: think about allowing sources/options.

All the other answers (so far) are absolutely correct: limiting sources/options is pretty common. It's a way to try to simplify the game, to prevent disparities in PC "power," and to downplay players' system-mastery as a component of the game.

But I'd encourage you to think about another common way* to think about character options/resources: as an allowed list rather than as a banned list.

In short, to begin any (usually homebrew, though it can work with published materials, too) campaign I first sit and talk with the players about setting: how high- or low-tech? What's the social organization? How common is magic? Are gods present and visible? Stand-out heroics or everymen trying to grind against the Empire? &c. &c. &c.

We then use this to devise a list of races, classes and possibly even equipment that's allowable in the game. For example:

We've decided to play a game of elves vs. orcs; the elvish kingdom is a theocracy that thrives on the wooded foothill slopes of the orcish mountains.

PC races allowed: high elf, eladrin, wood elf. Maybe the firbolgs also live in these foothills, so we'll allow that, too. Aasimar, for some of the religious connection?

PC classes: let's make this an overbearing theocracy (we don't want to sympathize too much with one side, after all) so Paladins and Clerics are in, Fighters and Rangers, but they find Druids ("beasties") unnatural and hunt them to the edge of existence. Maybe Warlocks, too. Barbarians we'll leave to the orcs, and bards... ooh, maybe those are the Aasimar--angels are messengers, after all! Wizard or Sorcerer let's make a pick as a table--maybe Wizard because they train in religious schools and we've already got a charismatic caster.

So our character generation options are Firbolg, Aasimar, or 3 type of elf. Classes are Bard (Aasimar), Cleric, Fighter, Paladin, Ranger, Wizard (probably only some schools).

And right there we've got more than enough to flesh out a party, we've got choices consonant with the setting and theme we've chosen together, and we're off to the races.

(This example may not be great--I whipped it up in 3 minutes. Hopefully it's enough for you to see what the idea is.)

In a half-dozen campaigns where I've used this approach I really like the players helping to create the setting/tone, character possibilities flowing from those conversations, the fairly unified party "feel" that comes from a small set of choices, and (as a player) the challenge that comes from playing a character that I might not have thought of if I had the whole set of books open to me.

_{* - I do it this way, and I've read others advise people on the internet to do it this way, so I'll use those two datapoints to extrapolate all the way to "common."}

Yes: it is helpful for the GM and it helps the group to grow together

Our first 5e group got together in 2014, before the PHB came out but after the basic rules had been published. Our DM was quite clear that there would be no feats until 4th level, no Variant Humans. There were few other restrictions, but even with his long experience with D&D reaching back to AD&D 1e, and his minimal participation in the play test, he was keen to make sure that we, as a group, did the crawl, walk, jog, run, sprint thing together. We all learned this edition of the game together as we went forward from 1st level into the adventuring world. I had not played D&D in over a decade - this incremental approach in getting back into the hobby made it a lot easier for me as a player. (Granted, I didn't make it easy on myself: I chose cleric, a spell caster, but it all worked out very well until Korvin died. grimace Rolled up a new character, and the Tempest Cleric was born...)

Fold in new material incrementally

When the Temple of Elemental Evil (free) supplement came out, our DM asked us to review the spells there and see if we were interested in any of them. He wanted to review them as well to make sure. This collaborative process is how my Tempest Domain Cleric ended up with the Thunderclap cantrip. (Not strictly a cleric cantrip, as presented ...). I gave up my Spare the Dying for that. We also agreed on a couple of later level spells that I could consider when I leveled up far enough. My brother's wizard got one spell from that supplement. (IIRC an earth elemental one, but I don't have his character sheet anywhere)

The primary reason our DM gave was "less stuff for me to keep track of" from his PoV. It worked out very well.

My brother did something similar when he began his campaign a few years later - limited character races available, limited deities (his own world), and "DM review of anything outside of PHB" before approval. He has mostly approved stuff, but that it was always a collaborative effort went over very well. No surprises, no "gotcha" stuff.

The DM can place whatever limitations he/she deems fit.

You can limit your rules to just the PHB if you so wish. You can limit the player's choices to just a handful or even one race or even limit the choices of classes.

So long as your players are on board and the limitations fit a story or narrative it is justifiable

As an example: The current main campaign I am running is much more segregated in the region the players have started in. Therefore, humans are the only race they were allowed to choose (except for one player that was allowed a gnome only because he gave me a convincing and plausible back story that fit). Elves are the primary antagonists and Dwarves are very far away. Classes were restricted based on the history of the region so Warlocks and Sorcerers would be persecuted, lynched or executed. They could choose them but I made it abundantly clear the ramifications if they did so. Wizards are "licensed" and watched closely and cannot inherit property nor own it directly (talking lands and titles here).

These types of limitations are a two-edged sword for simplicity

On the one hand you have fewer things to focus on (this makes focus on the story easier) but on the other you have to deal with players that want to explore certain options in other sources or even in the same source if you take it to the level that I did when building my new world. This sometimes causes push back - I know I have had some but now that they are learning more of the history of the region and the story involved they seem to have buy in.

The main goal is for everyone to have fun and you should bring up any limitations or house rules to your players. I do this as suggestions at the start but my players all know that I have final say. I bring them up because we have all played long enough that I know that they may find potential pitfalls to house rules that I may think could help simplify or make things more plausible.

Yes those are absolutely reasonable restrictions, but the burden of allowing additional official content need not fall heavily on you.

Keep in mind that it is primarily the player's obligation to keep close track of the precise workings of all their character abilities, not the DM's, so presuming you are not worried about official published WotC materials being unbalanced it probably isn't much of a burden to go ahead and let them use it. You are responsible for knowing the core rules and the content you bring to the table, not the ins and outs of every subclass and spell a player may use. To the extent you do need to learn it you will learn it as you go over the course of a long and hopefully rewarding campaign. This is the only way most of us learn what various spells, feats, and class abilities do. It is true that a character might catch you with an unanticipated spell, feat, ability, etc. that, from your perspective, breaks an encounter you set up, but they worked to get that. Being able to defeat problems in ways the "programmer" never intended is one of the joys of playing tabletop. And next time, oh next time, you will be ready for them.

Personally I would only worry if you are someone who is deeply uncomfortable not knowing a rule or if you are starting at a high level and will suddenly be bombarded by a dozen different things you've never heard of at once. Unearthed Arcana and homebrew is a different matter. That generally requires a lot more evaluation of balance, potential consequences, and potential rules ambiguities from a responsible DM and it is just complicating your life. I've only ever allowed one homebrew item (a special warlock's familiar) and that was because it really mattered to the player and he was able to make his warlock work, wait, and sacrifice for it.

I am by no means criticizing your decision to not use additional materials, I just think you and any other new DM who reads this deserves to know that they don't need to have mastered every aspect of the materials they allow to be a great DM. You learn it all as you go along.