Table Rules
Lets start with some ground rules, in addition to the rules of the PHB
Class Change
You can change your archetype. This will depend entirely on the change at hand, as changing a fighter’s Martial archetype is much more straightforward training compared to, say, a warlock shifting his patron. Other features, such as the warlock’s pact boon (blade, book, or chain) are easier to shift.
I will not allow you to remove a class entirely. However, if you multiclass into a new class, I will let you move levels over to the new class, as you train in the new class. You must retain at least 1 level of your original class, however. It will take a day of dedicated effort with a trainer (a member of the class with a higher level in the class than you), or a week without, to move 1 level over. I’m trying to avoid making you feel locked into the class you chose when months down the line you might be waiting to play something else.
Rule of Cool
While I tend to be very by-the-books on rules, I will give some leeway on certain abilities. However, I will hold spells to their written effects, but creative uses of those effects are allowed (ie: heat metal on a sword makes it deal heat metal’s fire damage on a hit, but the wielder still takes the damage as well) I will allow rules to bend, but not break without good reason.
Cross-over Skill checks
Certain skills, I feel, can have more than one ability score apply to it, while still making sense. Strength-based intimidation or dexterity-based athletics for example. I, as DM, will call for them as I see fit, though you can argue one way or another. Proficiency in intimidation, for example, will still apply whether it’s a charisma or strength intimidation check.
Fame and Infamy
Depending on the actions of the party, word of your deeds may spread, for better or for worse. Fame will help them find aid, potentially cheaper prices, and a guard might look the other way. Infamy will lead to fear and bias against the party. Prices may be higher, help may be harder to come by. Actions have consequences.
Weapon Enhancement
Weapons can be enhanced, through mundane or magical means. Mundane enhancement can be done by any seasoned blacksmith for cheap but does not bestow magical properties to the weapon. The weapon gains a +1-3 on damage, not attack, depending on the blacksmith’s smith’s tools check.
Revisiting Downtime Revisited
These haven’t had much use in our campaigns before. Here, I’ll be trying to give them purpose. Xanathar’s Guide gives a guide for crafting things, with gold cost, but the workweeks they outline feel too long to implement in an adventurous campaign. They say you can make 50gp worth of stuff in a week. I’m going to increase that to 500gp. You do need to pay out for the raw materials, which may become scarce. Though if the party doesn’t want to do this themselves, let me introduce:
Supporting NPC's
You will have the opportunity to have a Guildhall. Certain quests will result in an ally arriving at the hall as an employee of sorts. They are remote hands in crafting, though they cannot work without ingredients or at least a stipend for acquiring them.
Acquisition of Wealth and Power
Our campaigns seem to follow a formulaic loop: Adventure starts ►small fights ► Climactic Fight ► Reward (gold and magic gachapon items of varying usefulness) and multiple levels.
I’m going to be trying to break that a little. Not all fights mean gold. Not all adventures end in combat. Gold doesn’t come and go immediately between missions. Silver and Copper are valid currencies, with uses.
Levels are going to be Milestone, though since I don’t have a set story, I’ll keep track of XP so when you’ve earned a level you’ll get it. Think of it as a Morrowind/Oblivion “You should rest and meditate on what you’ve learned” popping up when it’s time.
Living World
The world is moving, whether you move with it. Wars are fought, battles won, problems dealt with, opportunities close, depending on the timing of your choices.
Homebrew
Case by case basis, inquire within.