I have not had a chance to run Caves of Chaos--which I plan on doing "by the book", such as it is--but my group is already working on a few houserules and some homebrew content for when I start running a converted Age of Worms campaign:
- Advantage/Disadvantage: Given that the math behind advantage and disadvantage is something like +4 and -3, I am going to change each instance to a +/-1. I might boost it to +/-2. I would also allow players to swap it out for a damage bonus instead, just to see what they do. The reason for this is that I think that multiple advantages and disadvantages should have a greater effect instead of a binary on/off.
- Equipment Costs: Overall I am changing costs largely to silver pieces and fiddling with them from there on out. I have no issue with adventurers coming back from dungeon crawls with "only" a crap-ton of silver instead of gold.
- Minor Actions: Spells and abilities that read "you can do this and still attack etc", like healing word, are just going to be categorized as Minor or Free actions. Less repetitive verbiage.
- Delay: You can delay your turn, which basically just reduces your Initiative count.
- Resistance/Vulnerabilities: Subtracts or adds a set value instead of halving or doubling it. Basically how 4th Edition handled it.
- Masterwork Weapons/Armor: There are scaling categories for masterwork items, making crafting skills and non-magical things more useful at later levels. Basically you can tack on attack and damage bonuses, as well as qualities like High Crit and Brutal from 4th Edition. Armor would get damage resistance, AC bonuses, etc. Some of these things might require special materials.
- Weapon/Armor Materials: Adamantine and mithril are not individual armors, but materials that armor can be made of. Currently adamantine grants damage resistance while mithril alleviates speed and skill penalties. Also adding in darkwood, dragon hide (for energy resistances), Baatorian green steel, etc.
- High Elf: Bonus against Charm effects instead of complete immunity. I think elves should have an edge, but not be able to ignore powerful fey that compel them (was not geas a charm-effect?).
- Hill Dwarf: Poison resistance instead of immunity. As assassin should still be able to poison a dwarf.
- Cleric Spells: This is almost exactly as I want it, save that clerics will have spell lists based on god or domain instead of having to set them. I might even make it more like a wizard, where they can learn new prayers.
- Herbalism: You cannot make healing potions. Instead you can spend an amount of sp to make a healing balm, which causes Hit Dice used during a short rest to restore an additional 3 hit points. Healing potions are magic items and I do not like the idea of someone with no magical aptitude being able to craft them. Plus it makes the feat more useful in low- no-magic campaigns like Dark Sun.
- Wizards: Still working on a spellcasting model that I like, but preparing spells is likely going away entirely. Just not sure if I want to do a recharging model, energy-gathering model, or a combination of both. Basically I want to not resort to a spell-point model unless I have to.
- Potion of Strength: Grants a bonus to Strength checks, melee attacks, and damage rolls. This makes it useful to everyone.
- Ray of Frost: Deals some cold damage and slows (half speed) instead of just dropping speed to 0. As is, it is too good against flying critters and it makes no sense that it can completely immobilize you, but you can still attack, and there is no physical trauma involved.
- Non-Ability Scores: Skeletons and zombies will still have an Intelligence score, albeit 1.
- Save-or-Dies: Going to go with scaling severity, here. As in, characters with x hit points suffer less severe penalties from attacks. So a medusa's gaze might slow then petrify a target who fails to Constitution saves, while a creature with 10 or less hit points, or who is bloodied, might be petrified instantly.
We have also cobbled together a bladesinger class (since I decided that a theme would not deliver enough, quickly enough to make it playable from the start), tieflings, changlings, and Wild Talent theme using existing things as a basis.