Can you multiclass the same class twice for different class features?

Question

The way that 5e works, each class has a sub class that dictates a heap of class features. The question here is generally, can a character of a specific class take levels in that same class in order to gain access to the low level features of another sub-class.

The best example of this would either be the wizard or the cleric taking additional levels of wizard/cleric in order to gain access to another domain or school.

Like can a Life cleric take levels of Storm cleric or similar?

If this were allowed, what would the effects be on Maximum spell level and other class level based abilities?

Answer 1

No.

PHB, Page 163, Multiclassing

With this rule, you have the option of gaining a level in a new class whenever you advance in level, instead of gaining a level in your current class.

This wording seems clear to me that you must choose either a different class, or gain a level in your current class. In the case of a cleric, this implies that you cannot start out at level 1 again (e.g. Cleric 1 / Cleric 1), as Cleric is not a new class.

Addressing the specific concerns of Cleric (Life) being the same class as Cleric (Storm), page 45 of the PHB states there are twelve classes, and then lists them in a table. In this table, Cleric is found only once, and there is no special mention of subclasses being different classes entirely.

This was officially clarified in the June 2016 Sage Advice:

Can I multiclass into the same class to pick more than one subclass?

Multiclassing is designed solely for taking different classes. For example, you can be a fighter/rogue, but not a rogue/rogue.

That said, I would talk to your DM. It may be reasonable, for example, to mix and match some of the domain powers at their discretion.

Answer 2

The DMG will have guidelines for creating your own classes and sub classes, as well as new domains such as the death domain. So this space is reserved for when the DMG is released. Until then, by the rules you can't mix sub classes (domains)

The rules for a cleric is that you may only use one domain:

As a cleric, you choose one aspect of your deity’s portfolio to emphasize,and you are granted powers related to that domain.

The rules for multiclassing is that you must choose a class that is not the class you currently have, or an additional level in one of your classes each time you gain a level.

With this rule, you have the option of gaining a level in a new class whenever you advance in level, instead of gaining a level in your current class.

This means that with the current rules, at no time do you have the option of picking up a new subclass or a new domain. But with the DMG other solutions will become available. The Players handbook mentions that there are 12 classes, and does not list any of the class variants or the choices within a class as a new class.

The DMG also has a lot of utilities in it, like for dungeon creation, adventure creation, creating monsters, creating spells, even if you wanted to create a character class. It's not quite the point-buy system from 2nd Edition, but it does say things like "Well if you want to create a class for your campaign then here's a good way to approach it.
From The Escapist Magazine interview here

Answer 3

RAW, it's not allowed and there's no real benefit besides gaining new domain spells and features.

In any case, negotiate a Homebrew Cleric Domain with your player by mixing from the Domains he/she likes to tailor something that fits the character but isn't game breaking and makes sense. Think of it like Backgrounds.

You can also try and come up with one of your own, but balance could be an issue that should be discussed with the other players; usually, when you start using homebrew or house rules on your campaign, the other players might get hyped, and want some of it too, which can lead to some group stability issues.

Answer 4

Quoting from PHB pg 59:

As a cleric, you choose one aspect o f your deity’s portfolio to emphasize,and you are granted powers related to that domain.

So, NO, you cannot multiclass into the your same class, and NO, you cannot take additional Domain