I had very rough hybrid rules. I never went far with them because it felt too easy to abuse, I think. The drawback to this method, as always, is complexity.
The goals I had were:
- Multiclass characters should sacrifice overall power in exchange for increased versatility.
- Players should make a class selection at character creation time, and then follow that progression throughout the game.
- The character advancement table should be the same. The system should use the standard XP tables, standard proficiency bonuses, and standard hit dice progression. If a level 9 Wizard has a +4 proficiency bonus on weapon attacks, it doesn’t make sense that a level 10 Fighter/Rogue would have less than that. Retaining XP progression means that all experience reward methods continue to work.
- The system should be as simple and straightforward as possible, introducing as few new game elements as it can. The design should favor less elegant designs that reuse existing elements of the game instead of creating entirely new designs.
- Retain rules from a la carte multiclassing for stacking and ability score prerequisites.
Hybrid Multiclassing Rules
Select two or three classes. Then:
1. Multiclassing sacrifices the benefits of specialization, so multiclass characters never gain any abilities from archetypes (though see the feat below). You should select a subclass normally; you just don’t gain any abilities as a result of that selection. This harms some classes much more than others. Ranger in particular is significantly weaker than it would be otherwise.
2. Skill proficiencies: Select two of your classes. Select two skills from either of the skill lists for the selected classes. If one or more of the selected classes is Bard, Ranger, or Rogue, instead select three skills from either of the skill lists for the selected classes.
3. Save proficiencies: Select one of your classes. Gain the save proficiencies for that class.
4. Weapon, armor, tool, and vehicle proficiencies: Combine the weapon, armor, tool, and vehicle proficiencies of all your classes.
You gain levels normally, and your level is used to determine your proficiency bonus and hit dice. This level is referred to as you "character level". However, your class ability level is reduced, so you will not gain new abilities each character level. This second level is referred to as your "class level".
5. Proficiency bonus: Your character level determines your proficiency bonus. A level 11 Fighter/Wizard has the proficiency bonus of a level 11 character.
6. Hit dice: Alternate hit dice each level, so a Fighter/Wizard would use d10, then d6, then d10, then d6, etc. A Fighter/Rogue/Wizard would use d10 -> d8 -> d6 -> d10 -> d8 -> d6, etc. You always rotate your HD earned like this. A level 13 Fighter/Rogue/Wizard would have 5d10 + 4d8 + 4d6 Hit Dice. You always gain the largest hit die first.
7. Use the chart below to determine your character's class ability levels. Your character has the abilities of the class ability level. Thus, a level 5 Fighter/Wizard has a class ability level of 3, and has the class abilities of a 3rd level Fighter, and the class abilities of a 3rd level Wizard. However, such a character would have a +3 proficiency bonus that a 5th level character has, and would have 3d10 + 2d6 Hit Dice from levels. Again, you never select any class paths, so you never gain any abilities tied to class paths (though, see the feat below).
| Character Level | Proficiency Bonus | Number of Hit Dice | Double Class Hit Die | Triple Class Hit Die | Fast Class Ability Level | Fast Class ASI | Medium Class Ability Level | Medium Class Ability Level Rounded | Medium Class ASI | Slow Class Ability Level | Slow Class ASI |
| 1 | +2 | 1 | 1st Class | 1st Class | 1 | | 1 | 1 | | 1 | |
| 2 | +2 | 2 | 2nd Class | 2nd Class | 1 | | 1 | 1 | | 1 | |
| 3 | +2 | 3 | 1st Class | 3rd Class | 2 | | 1 | 2 | | 1 | |
| 4 | +2 | 4 | 2nd Class | 1st Class | 3 | | 2 | 2 | | 1 | |
| 5 | +3 | 5 | 1st Class | 2nd Class | 3 | | 3 | 3 | | 2 | |
| 6 | +3 | 6 | 2nd Class | 3rd Class | 4 | YES | 3 | 4 | | 2 | |
| 7 | +3 | 7 | 1st Class | 1st Class | 5 | | 4 | 4 | YES | 3 | |
| 8 | +3 | 8 | 2nd Class | 2nd Class | 6 | | 4 | 5 | | 3 | |
| 9 | +4 | 9 | 1st Class | 3rd Class | 6 | | 5 | 5 | | 4 | YES |
| 10 | +4 | 10 | 2nd Class | 1st Class | 7 | | 6 | 6 | | 4 | |
| 11 | +4 | 11 | 1st Class | 2nd Class | 8 | YES | 6 | 7 | | 4 | |
| 12 | +4 | 12 | 2nd Class | 3rd Class | 9 | | 7 | 7 | | 5 | |
| 13 | +5 | 13 | 1st Class | 1st Class | 9 | | 7 | 8 | | 5 | |
| 14 | +5 | 14 | 2nd Class | 2nd Class | 10 | | 8 | 8 | YES | 6 | |
| 15 | +5 | 15 | 1st Class | 3rd Class | 11 | | 9 | 9 | | 6 | |
| 16 | +5 | 16 | 2nd Class | 1st Class | 12 | YES | 9 | 10 | | 7 | |
| 17 | +6 | 17 | 1st Class | 2nd Class | 12 | | 10 | 10 | | 7 | |
| 18 | +6 | 18 | 2nd Class | 3rd Class | 13 | | 10 | 11 | | 8 | YES |
| 19 | +6 | 19 | 1st Class | 1st Class | 14 | | 11 | 11 | | 8 | |
| 20 | +6 | 20 | 2nd Class | 2nd Class | 15 | | 12 | 12 | YES | 9 | |
For the curious, the fast class level formula is character level * 0.75 rounded down. Medium is class ability level = character level * 0.60 rounded down or up (hadn't decided) and slow is 0.45 rounded down. Minimum level is 1, obviously.
8. When a character gains an ASI at class levels 4, 8 and 12, the character gains only
one ASI, not an ASI from each class. Similarly, abilities described in the multiclass section as overlapping, such as Extra Attack, still overlap with hybrid multiclassing.
9. For spellcasting slots, use your character level and the combined spellcasting chart in the multiclassing chapter to determine your slots. If one of your classes is Bard, Cleric, Druid, Sorcerer, or Wizard, then your character slots are determined by your character level. If none of your classes is Bard, Cleric, Druid, Sorcerer, or Wizard and one of your classes is Artificer, Paladin or Ranger, you have spell slots equal to half your character level. For example, a level 10 Ranger/Rogue has class abilities as a 7th level Ranger and as a 7th level Rogue. However, for spellcasting, Ranger lets you use half your character level instead. You would use your character level 10 divided by 2 = 5 and would use the level 5 chart for determining your spells per level. For another example, a level 11 Fighter/Wizard has a class ability level of 8. You would use the level 11 on the spellcasting chart to determine the number of spell slots per day, but would prepare spells as an 8th level Wizard.
10. Some other class abilities may also use the class ability level instead of the character level. [I had some ideas what these should be at one point, but I've forgotten.]
At this point, I would do some playtesting. Where things are at above is what I think would be slightly overpowered. My guess is that there's some discrepancy in balance between the two class and three class level charts. I'd step down the factor 0.05 each time. The balanced factor might be closer to 0.15 lower than it is above, so two class might need to be down to 0.60 (level 20 = 12), and three class might need to go down as far as 0.45 (level 20 = 9).
The skill, save, and proficiency rules could be made a whole lot more complex to add flexibility, but I don't really feel like that's worthwhile.
Available Class Combinations and Balance
You'd have to make some special rules, I'm sure. Warlocks and clerics are a bit generic without the abilities from their paths. Certain ability combinations are really good, like Fighter/Paladin character level 15 on fast, or Fighter/Rogue/Paladin at character level 19 on medium. My guess is that there are some combinations that are simply too good, so you might need to limit the classes or class combinations in some way.
Some tables will discover that certain class combinations are significantly more powerful or less powerful than others. Therefore, it is recommended that tables restrict players to selecting class combinations from a prescribed list rather than allowing any combination of classes. Warlock and Paladin offer significant advantages, while Ranger has significant disadvantages due to the class structure.
New Feats
Hybrid Specialization
Prerequisite: Hybrid multiclassing, Class ability level of 4 or higher
Choose one of of your hybrid classes. You gain all class features and associated benefits that you would gain for your chosen archetype for that class up to your current hybrid class ability level. As your hybrid class ability level increases, you gain any new features from the chosen class’s archetype at the appropriate hybrid class ability level.
