So then, here we go. Ever since 2e the idea of combining two classes and leveling up in them simultaneously has always been something players have wanted to do. Whether it's for high-powered gaming, options shenanigans or just covering apparent weaknesses in two classes with their apparent strengths, "dual classing" as it was called in 2e has always been an attractive option. Of course such things have always changed the game a little bit because of how much more powerful characters become. In 2e this was handled by splitting your experience between classes, cutting your health per level in half for each class's hit dice (but getting both), which typically left you a level behind in both classes. In 3.5 you mix and matched class features, took the better of your class's saving throws, hit dice size and skill points, and... I'm not sure how it functioned in 4e, or even if there were codified rules.
5th edition, being a new system with new class mechanics and rules, begs for a new gestalt system. In fact, there were even rumors that it might show up as an official variant in the DMG a year before the book's release! ... And then it didn't happen, which leas us to here. I'll be going through the steps of how to combine classes, how to adjust the challenge rating of monsters that the party faces (or determine the effective level of the party), and how to handle things such as starting proficiencies, spell slots and ability score increases. If anything is missing or a part of the rules seems to be a bit off, please inform me and tell me why or make your own rules suggestion! Now then, let's get this show on the road!
Proficiencies, hit points and class features
Now to start off we will be going through the more simple systems, the ones that are more concrete and easy to manage than, say, ability score increases and starting skill proficiencies. These non-skill proficiencies, hit points, class features and spell slots tend to be the best of your class options. Now then, specifically:
Over all class level: What that means is that gestalt characters basically have two "sides" to them, both of which level up at the same rate and grant you features at the same time. However, these sides do not stack for determining your over-all class level. When determining your over all class level (for challenge rating, hit die and hit points), take the converted class level of one side or the other.
Backgrounds: You benefit from one background, as normal.
Hit points: You only get one hit die each time you level up, using whichever class has the higher die size.
Hit dice: You have one hit die per level up, using whichever class has the higher hit die.
Saving throw proficiencies: Select any three saving throw proficiencies that your classes grant. If your classes both provide the same save proficiencies, then you only get those two proficiencies.
Weapon proficiencies: Use whichever class has more proficiencies.
Armor proficiencies: Use whichever class has more proficiencies.
Proficiency bonus: Your proficiency bonus is the same as a normal character of your class level.
Tool proficiencies: You gain all tool proficiencies provided by both starting classes.
Channel divinity: If you get channel divinity from multiple classes, you have access to all channel divinity options your classes provide. However, when determining how many uses of channel divinity you have/ short rest, use the class that gives you the most charges.
Spell slots: You gain the spell slots of whichever class grants the faster progression. Pact magic slots stack with normal slots, but mystic arcanum does not grant any additional spell slots of level 6 or higher.
Spells known: For classes such as sorcerers, bards and warlocks who do not use a spell book or have access to their entire spell list, both classes gain their normal spells known from their respective spell lists.
Prepared spells: For classes that can change their spells after each long rest, a character can memorize a number of spells, they memorize spells for each class individually, using their class level + The casting stat of each class.
Extra attack: The extra attack feature does not stack between gestalt classes. Fighters still get their full progression.
Unarmored defense: Unarmored defense does not stack (as normal). Instead, choose the formula that grants the highest AC.
Subclasses (Variant rule): You may choose to either take a subclass for each class on both sides of the gestalt, or you may choose to forgo selecting subclasses on one side of the gestalt to select a second one for your other class. For example; Let's say that you are playing a Monk // Rogue. You may choose to forgo selecting a rogue subclass (and all subsequent subclass features) over the rogue's career to select a second subclass for the monk at level 3, gaining all subsequent subclass features from both monk subclasses at the appropriate levels.
Effective character level: For purposes of figuring out what level a character effectively is when designing encounters, it is important to remember that the scaling effect of a gestalt character will be even greater than normal. However, at low levels this is less pronounced as characters still only have just as many spell slots and hit points as they would normally. So as a general rule of thumb the extra scaling should go something around this:
-Level 1-2: No difference in effective level
-Levels 3-5: Treat character level as 1 higher
-Levels 6-10: Treat character level as 2 higher
-Level 11-15: Treat character level as 3 higher
-Level 16-20: Treat character level as 4 higher
Skill Proficiencies and Ability Score Increases
These two things are... well, they would be easy to handle normally, I will admit. However, instead of the bog-standard version (take the one that gives you the most skill proficiencies/ ability score increases and just run with it), I thought about it for a while and came up with a few different variants that could work for different tiers of play. Let's be honest after all... if you are using the gestalt system, you are already going for a more powerful build. You might as well go all the way and get some "tiers of silliness" that reach the epic proportions.
So there are three tiers, standard, high-fantasy and mythic. Each will be explained below (along with their mechanical effects):
Standard tier
While still exceptional even among heroes, the party's training does not start out (nor reach such silly heights) as to be completely beyond or even equal to the capabilities of two other equally trained heroes. This works well in most worlds, and should be considered the "standard" for gestalt.
Skill proficiencies: You gain the higher number of proficiencies available between classes, chosen from either skill list.
Ability score increases: You gain one ability score increase at class levels 4, 8, 12, 16 and 19. You only gain extra ability score increases if a class gives them at a different level (like the fighter at 6 and 10, and the rogue at 10).
Effective character level: Same as typical gestalt.
High-fantasy tier
Truly remarkable people who go down in legend as being the best a mortal can hope to accomplish, this is the creme of the crop. Often the equal of two lesser men in all but their durability and ability to be two places at once (and sometimes besting them at that), those who find themselves in the high fantasy tier are very much more than your average man. More likely to be found in fantastical worlds where magic and villains ooze out of the woodwork, and a bit more powerful than even a normal gestalt character. This tier requires the feats variant to be used.
Skill proficiencies: You may select a number of skill proficiencies equal to the proficiencies provided by both of your classes. The maximum number of skills you can start with from your classes in this way is 5.
Ability score increases: You gain two ability score increases at class levels 4, 8, 12, 16 and 19. One of these ability score increases at each level you get them
must be spent on increasing your attributes, while the other one
must be spent on a feat. Extra ability score increases granted by classes such as fighter and rogue still only grant a single ability score increase that may be spent on attributes or feats as normal.
Effective character level: Increase the effective character level of a high-fantasy gestalt character by an additional 1 at level 8. At level 16 increase the effective character level by an additional 2.
Mythic tier
Heroes so great that from their very birth they were destined for legends. Able to attain the feats of the greatest individuals from the beginning of their adventuring careers, heroes of the mythic tier are a good deal beyond the achievements of lesser mortals. Characters within this tier are more at home in crazy campaigns where the world is filled with darklords and cosmic horrors. You know, a world where even the most ludicrously optimized of heroes can be challenged. This tier requires the epic boons variant to be used.
Skill proficiencies: You may select as many skill proficiencies as your classes provide. At the moment the maximum is 7, but honestly... it's not too unlikely that another 4 skill class will come out one of these days, and there is no hard limit on how many skills you may gain from your classes at level 1.
Ability score increases: You gain one ability score increase and one epic boon at class levels 4, 8, 12, 16 and 19. Your epic boon may be spent on increasing a score that is already at 20, on an epic boon listed in the DMG, or on any epic boons your DM may design. Extra ability score increases from classes such as the fighter and the rogue grant
two ability score increases each, one of which
must be spent on attributes and one of which
must be spent on a feat.
Effective character level: A character of the mythic tier increases their effective character level by an additional 1 at levels 4, 8, 16 and 19 (to a total of an additional 4 at level 19).
Multiclassing
General rules: You may only multiclass on one side of the gestalt. The sum of your multiclass levels cannot be greater than the over all class level on the other side of your gestalt.
Subclasses (Variant rule): If you decide to sacrifice subclasses on one side of your gestalt, you may only multiclass on the side that is not eligible to receive subclasses.
The sublass variant has some problems if you use multiclassing. If you allow the side with access to double subclasses, you can potentially get a lot of subclasses very quickly, while if you grant multiclassing on the other side without specifying that all classes on that side lose subclasses, then a player might think they can just dip one or two levels of a class on that side (for say, action surge from a fighter...) and then multiclass out to a different class without any penalty for a net gain of 18-19 extra levels of a "free" subclass. Hence the specification.
So, comments? Questions? One of the 50,000 things I probably missed?
