Base Class: Rogue
You have spent your life hiding in the mists. Swirling clouds of fog are your friend, a protective covering that hides you from prying eyes. You become well-versed in navigating without relying on your sight and striking foes you cannot see, while remaining hidden from view.
Mistweaver
Beginning at 3rd level, you can summon mists at any time. You gain the ability to cast fog cloud, with the target being self. Once you have used this feature a number of times equal to your Intelligence modifier, you must complete a long rest before you can use it again.
One with Shadows
Starting at 3rd level, you are comfortable when surrounded by fog. When you are surrounded by mists, you gain advantage on Dexterity (Stealth) checks. In addition moving through nonmagical difficult terrain costs no extra movement if you are under the cover of mist.
One With Shadows
Starting at 3rd level, you are comfortable when surrounded by fog. When you are surrounded by mists, you gain advantage on Dexterity (Stealth) checks. In addition moving through nonmagical difficult terrain costs no extra movement if you are under the cover of mist.
Mistsense
Starting at 9th level, you have learned the nuances of the mist. Once in the mist, you gain mistsense. Mistsense activates once you enter the mist, allowing you to use your bonus action to make a DC 15 perception check. On a successful check you can tell the location of any creature within 20 feet within the same mist cloud.
Mistblade
Beginning at 13th level, you can create a weapon out of mist, While in the mist, you gain access to a mistknife, a weapon made entirely out of mist. It has all the properties of a shortsword except that it leaves no visible wounds on the target. Instead, the damage it deals is internal and causes the target to bleed for an additional 1d4 health at the beginning of each of their turns for three rounds.
Toxic Fog
At 13th level, you can infuse your fog with the Cloudkill ability, spreading poison through your mist while you yourself are immune to its effects.
One With Mists
At 17th level, you are so familiar with the mists that you can melt into them yourself. You can cast the spell Gaseous Form on yourself at Will.
I'm a little confused about how this works. The Fog Cloud spell creates an area that is heavily obscured, and all creatures within are considered Blinded. The blinded conditions grants a creature disadvantage on their attack rolls, and attack rolls made against that creature have advantage. But this would then make getting Sneak Attack near impossible to trigger, because the caster of Fog Cloud, the rogue, is affected as well by the blindness. This means all of their attacks would have disadvantage, and any advantage they might get would cancel out. You wouldn't get Sneak Attack from the negated advantage.
According to the rules on advantage and disadvantage (PHB 173):
"If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa. In such a situation, you have neither advantage nor disadvantage."
How do you determine the saving throw DC for Toxic Fog?
I like this concept, but the execution confuses me. You're an expert on making fog and hiding in it... and then what? You're blinded, so you're not going to be attacking anyone effectively. You're not actually any more proficient at fighting in your fog than anyone else, and now you've blinded all your teammates as well. If you're fighting something with blindsense or tremorsense, you are outclassed in your own fog. At least until level 14 when you finally get Blindsense.
I think you were trying to solve this with Mistsense, but A) you already know locations of creatures even when you can't see them unless they are specifically using the Hide action, B) knowing a creature's location doesn't remove disadvantage on attacks against them, and C) you shouldn't have to wait until level 9 to get your main schtick to work.
And if you're trying to use it to sneak around, everyone can still see the unnatural fog cloud moving through the courtyard. Smart enemies could even figure out your position even when you Hide because the cloud is centered on you, so you are always in the very middle of it.
But like I said, the concept is cool. Anyone wanting to try this out, I'd recommend looking at the Marine Layer ability of the Oath of the Open Sea paladin. It has a pretty good mechanic for fog that doesn't leave you helpless in it. I think applying that here would help the subclass to perform the way I think it was intended to.
I have a question about One With Mists. It says you can cast Gaseous Form at will i'm wondering if it still has the VSM component
One With Mists
At 17th level, you are so familiar with the mists that you can melt into them yourself. You can cast the spell Gaseous Form on yourself at Will.
Not likely, for one Taking20 is selling his class so unless someone ganked it and posted it as theirs here it isnt his. Secondly the skill sets aren't as fleshed out here as what he has available.
Is this Cody's (Taking20) ranger?
This is a really cool concept! I love the Mistblade even before I use this class. And yes, I do know the people who created it.