Probably going to be DMing soon and have browsed the books slightly... But what should I read to prepare myself for DMing? I likely won't have time to read everything as I would like to, but I have a grasp of the absolute basics (Advantage, Disadvantage, Proficiency, Character Creation) and experience from Pathfinder.
Mechanically, As a DM read the bit about encounter design from the DMG that tells you that numbers matter in a fight and the action stuff from the PHB -one action (incorporating an interaction with one object) , move, maybe a basic action on your turn, one reaction on others turn.
The starter set and the Lost Mine of Phandelver in it is the best way.
The player booklet in that book is great to read also. It has the combat actions etc. And the conditions is on the back of one of the books.
It's well laid out, I love it.
CRs work kind of different. In one DM's first attempt with 5e, he set the party of four lvl4 PCs against 4 CR4 monsters, and we nearly wiped (my Barbarian died and he was effectively only taking half damage due to rage, Paladin and Blade Warlock were making death saves, and the Tome Warlock closed out the fight in single digit health).
Yeah, 5Ed CR = a very significant challenge for 4 PCs, not a relative cakewalk for 4 PCs (like PF).
Definitely look into actions per round and what all the actions are (Dodge, Dash, Disengage, Hide, and Dodge).
Remember, there are no move-equivalent actions anymore. You can move, do your action, and continue to move up to a total distance equal to your speed.
A character on its turn can move, manipulate an object (open a door, draw or stow a weapon, pick up a stick, etc,), take an action, and a possible bonus action (Note: some bonus actions, such a monk's flurry of blows, allow you to make 2 attacks. Similarly, at 5th level, many warrior-type classe can make 2 attacks as their Attack action.)
Sometimes, when it's not your turn, you can use your reaction, usually for making an Opportunity Attack, but sometimes to cast a spell like hellish rebuke or use a class feature like the Light cleric's Warding Flare.
Be generous with Advantage & Disadvantage and especially with renewing Inspiration. Encourage short rests; I think 5th Edition "Adventuring Day" encounter design is supposed to go:
Encounter
Encounter
Short Rest
Encounter
Encounter
Short Rest
Encounter
Encounter
Long Rest
Repeat.
It may vary depending on what classes are in your party. Some classes really rely on short rests to be effective all day long, like warlocks, and a lot of other classes really benefit from them (5th+ level bards, Divine Channeling clerics, wildshaping druids, action surging fighters, ki-using monks, Divine Channeling paladins, and Arcane Recovering wizards).
Also, pay attention to all the Concentration spells (and make a note Concentration means something TOTALLY different from 3.5/PF Concentration rules (which are now Constitution saving throws)). Remember that a spellcaster can have 1 spell active that requires Concentration, but Concentrating on a spell does not require an action itself. So a spellcaster can Concentrate on one spell and still cast spells that do not require Concentration without losing your Concentration on the original spell.
Also, if a spell has a casting time of 1 bonus action, you cannot cast another spell of 1st level or higher on your turn, but you CAN cast a cantrip if you want. Or hit something with a stick, or Dodge, or Hide, or Dash, etc. etc.
EDIT:
Another thing to look at is Large and larger monster's reach. It's a lot rarer for Large creatures to have exceptional reach.
Opportunity Attacks are generally only provoked when a creature LEAVES an opponent's threatened area. It's perfectly "safe" to circle around or move within an opponent's threatened area. Also, you usually don't provoke an OA when another creature makes you move, such as with the Push combat action or the thunderwave spell.
RE-EDIT:
When it comes to magic items, be wary of the ones that give numerical bonuses. "Bounded Accuracy" is a thing for a reason. However, because 5th Edition doesn't rely on "The Big Six," it gives you, as the DM, to drop fun and interesting magic items. For example, I have a hill dwarf Life cleric, and instead of worrying about getting Wisdom maximizers and lots of armor and weapons and cloaks and rings of protection, my character has a Ring of Swimming and a Medusa Mask that petrifies opponents and protects me from visual effects. Magic items can add a lot of versatility to the PCs. Our hunter ranger archer has a Horn of Valhalla. Fun stiff like that.
Yeah, 5Ed CR = a very significant challenge for 4 PCs, not a relative cakewalk for 4 PCs (like PF).
^ This.
The conversion from 5E to PF in terms of CR is +2 (Challenge 0-10) to +3 (Challenge 11+). E.g. a 5E CR2 ogre plays like something CR4 would in Pathfinder (like a stock ogre with a barbarian level added). I would also suggest caution when putting together encounters, the (somewhat weird) encounter building tools and Adventuring Day lean quite far on the brutal-grind-fest side of play. Levels 1-2 are especially lethal.
Additionally: When it comes to monster design, gut instinct (and your own experience with 5E combat) is the best guide there is. 5E's approach to a lot of things is not systemic, but instead works on the old-school "This looks about right". I'd strongly suggest ignoring the monster design section of the DMG, personally.
Raynulf:
You're right. The monster "design" "guidelines" are a mess. I don't even know why monsters have Hit Dice in 5th Edition. How many of them REALLY get a chance to take a short rest? The size-based hit die is neat in theory, but often it just means "equivalent" CR monsters have 10d4, 6d6+6, 5d8, 4d10+4, 4d12, or 2d20+4 based on size.
One issue I've had with 5e is to make that "recommended adventuring day" happen. Nova:ing wizards want to go long rest early which hurts (comparatively) champions and warlocks.
Also: When your player of a Level 3+ Caster tries to use witch bolt as a 2nd level slot to do 2d12 lightning damage per round, that is not actually how the spell works. Arguably it's how the spell should work, because as-written it is terrible... but as it stands it only does increased damage on the initial strike - the automatic damage each round is only ever 1d12.
(This one comes up a lot).
I read the rules for reach weapons, but I'm not sure I have it right. Does a reach weapon (not just natural reach) threaten both ten and five feet away?
Correct.
Opportunity Attacks (as they're called in 5E) work differently to Pathfinder: An enemy provokes an OA from you only when they leave your reach*. This means they can always approach you unmolested, regardless of reach, but if they try to move away you get a parting shot.
*There are exceptions:
- If they use the Disengage action, they don't provoke an OA.
- If you have the Sentinel feat, and they disengage, they still provoke an OA.
- If you have the Polearm Master feat and wield an appropriate weapon, they provoke an OA when they enter your reach.
Noting you only ever get 1 OA as it consumes your Reaction.
I read the rules for reach weapons, but I'm not sure I have it right. Does a reach weapon (not just natural reach) threaten both ten and five feet away?Correct.
Opportunity Attacks (as they're called in 5E) work differently to Pathfinder: An enemy provokes an OA from you only when they leave your reach*. This means they can always approach you unmolested, regardless of reach, but if they try to move away you get a parting shot.
They can also circle around you (and you around them) without any AOs happening as long as neither leaves the other's reach.