Unarmored defense and tortles

just as a question for all dms what is your ruling on unarmored defense and tortles natural armor. I had a charecter concept as a tortle barbarian wih a theoretical ac of 21 at level one (10+4 con+7 natural armor) so how woould you go about this

yeah Nah.

Rules for AC say you choose on method of calculating it so you choose between the two options you have.

Barbarian = While you aren’t wearing any armor, your base Armor Class equals 10 plus your Dexterity and Constitution modifiers. You can use a Shield and still gain this benefit.

Tortle = Your shell provides you a base AC of 17 (your Dexterity modifier doesn’t affect this number). You can’t wear light, medium, or heavy armor, but if you are using a shield, you can apply the shield’s bonus as normal.

It is either 10+4 con+? Dex

or 

10+7 natural armor

Quote from GraysonMabray46337 >>

just as a question for all dms what is your ruling on unarmored defense and tortles natural armor. I had a charecter concept as a tortle barbarian wih a theoretical ac of 21 at level one (10+4 con+7 natural armor) so how woould you go about this

Estaln is correct, but just to expand a bit: the key here is that there is no "+7 natural armor". Nothing in the Tortle species features say you get "+7" to your Armor Class. It says that your Armor Class is 17. As a Tortle Barbarian, you have three ways you can calculate your base AC:

• 10 + Dexterity modifier (this option is available to anyone who is not wearing armor)
• 10 + Dexterity modifier + Constitution modifier (only Barbarians have this option)
• 17 with no modifiers (only Tortles have this option)

These are mutually exclusive options; the rules don't allow you to mix and match pieces of them. You choose which one you want to use — and, presumably, you're going to choose the one that results in the highest total, which at low levels will almost always be the Tortle's flat 17.