Where can I find Matt Mercer's Critical Role House Rules?

Question

I'd like to use house rules from Critical Role in my own campaigns, and while we may tweak them once we've tried them, they seem to work well for Matt and his players, so what they use would be a good starting point. I've seen Matt Mercer's homebrew content (as used on Critical Role) mentioned on several forum threads, but aside from the resurrection rules being referred to as "famous" I've not found a lot of detail.

Is there a comprehensive list/details of these rules (or at least of the most notable ones?) If so, where can it be found?

Because I want to start from exactly what they use, I'm looking for something verifiable. That means that rules defined by someone watching the show and working out a best guess on what they are isn't a good answer, while either a purchasable resource (if it's included in the Tal'Dorei Campaign Guide, for example) or something otherwise directly from/endorsed by Matt Mercer himself would be a good answer.

So I'm looking for something that is:

1. Not a breach of copyright
2. Verifiably what Matt Mercer actually uses/wrote

Answer 1

Some are listed in the Tal'Dorei Campaign Setting (though they may be slightly different from those used in play)

As you guessed, some of the house rules used in Critical Role do indeed appear in the Tal'Dorei Campaign Setting book. However, the book does not clearly distinguish which of the listed house rules or homebrew feats are actually house rules used in Critical Role, or whether the version of something in the book actually matches the version used in actual play during Critical Role.

Michael Liu's answer links to sources on /r/CriticalRole on reddit where some of the Critical Role houserules are listed. Of those, the following ones appear in the Tal'Dorei Campaign Setting as feats:

• Matt Mercer allows his characters to drink potions as a bonus action. This appears in the book in the form of the Rapid Drinker feat (p. 109):

  Through a lifestyle of hard, competitive drinking, you’ve learned how to quaff drinks at an incredibly accelerated pace. You gain the following benefits:

  • You can drink a potion as a Bonus action, instead of as an action.
  • You have advantage on any saving throws triggered by ingesting an alcoholic or dangerous substance.

• Mercer also allows characters to cast multiple spells per turn (without changing their casting times), ignoring the 5e rules limitation around bonus-action spells. This also appears as the Spelldriver feat (p. 109):

  Prerequisite: Character level 8th or higher

  Through intense focus, training, and dedication, you’ve harnessed the techniques of rapid spellcasting. You are no longer limited to only one non-cantrip spell per turn. However, should you cast two or more spells in a single turn, only one of them can be of 3rd level or higher.

The Tal'Dorei Campaign Setting book also has an entire section in the same chapter (Chapter 3) on "Optional Campaign Rules and Guidelines". Within that chapter, it suggests that when running games with larger parties, the DM may want to give out the Rapid Drinker feat (or the equivalent primary benefit) and eventually give out the Spelldriver feat at 8th level. It also lists accelerated downtime mechanics and Matt Mercer's alternative resurrection rules. All of these seem to generally match the house rules listed in Matt Mercer's comment on /r/CriticalRole that Michael Liu's answer links to.

This section is accompanied by the following sidebar:

Optional Rules of Critical Role

For those who have watched along with our adventures, you may see some of these optional rules as familiar. Many of the elements included in this chapter are based on or retooled versions of the house rules we tried within our own campaign. Some have undergone a number of changes for balance as we try new things and learn from our experiences. For those that are curious, the ones we utilized within our own game are Rapid Quaffing and Multi-Spell.

As such, these optional rules may not perfectly match the CR houserules as used in actual play, but they are a refined version of those houserules.

Answer 2

Matt Mercer made a comment on the Critical Role subreddit two years ago outlining his major rules changes by his recollection (including his rule for resurrection):

Here are all the major ones I can recall!

• All of the Gunslinger Martial Archetype for Fighters.
• You can cast two spells in a round, so long as one of them is 2nd Level or lower.
• Pulling out and Drinking a Potion yourself takes a Bonus Action.
• Crafting Magical Items, Potions, etc takes only 1/4 – 1/8 of the time in the PHB.
• Ranger Animal Companions are slightly buffed due to underpowered elements.
• Short Rests are around 15-20 mins.
• Intimidating Presence (Barbarian Ability) is based on Strength, not Charisma.
• Inspiration acts as a +1d6 they can add to a roll.
• Resurrection magic require a Skill Challenge by the party. DC starts at 10, 3 checks set the final DC. Successes lower the DC by 3. Failures increase the DC by 2. Then, a final Resurrection Roll is made by the DM (straight d20) to signify if the player’s soul returns, or is lost.
• Critical Hits take the damage dice and doubling them (saves on time).

The subreddit's wiki has a compilation of that information and more from Matt's Twitter and Critical Role episodes themselves.