Name: Morph Exterior

Level: 3

School: Transmutation

Casting Time: 1 action

Duration: Concentration, 1 minute

Range: Self

Components: V S M (a piece of obsidian, a sycamore tree branch, or a sample of Ochre Jelly ooze)

This spell allows you to alter the outer layers of your body to adapt to the battlefield. When you cast this spell, choose one of the following options:

Stiff Exterior: Your skin hardens, becoming like porcelain in texture. You gain resistance to piercing damage and vulnerability to bludgeoning damage.

Soft Exterior: Your skin gains a cushioning, almost wooden layer. You gain resistance to bludgeoning damage and vulnerability to slashing damage.

Slippery Exterior: Your skin exudes a slimy film out of every pore. You gain resistance to slashing damage and vulnerability to piercing damage.

Classes: Artificer, Sorcerer, Warlock, Wizard

I came up with this spell a couple days ago. Since it's pretty much just a worse version of stoneskin, I originally thought that it should be a 3rd-level spell, but then I thought that the vulnerability along with the reduced duration should make it a 2nd-level spell. So, I removed the costly material component and replaced it with more flavorful components, which could just be circumvented with a focus or component pouch. But I still think the drawbacks are worthy of bringing it down to 2nd-level.

  • \$\begingroup\$ One possibility to make this more worth it is for each of them to give resistance to two types of attack while having a vulnerability to the third... \$\endgroup\$ Sep 24, 2021 at 13:29

2 Answers 2


Stoneskin at least gives you the option to ward someone else, which is a great way to get around "every time this spell is useful, I'm rolling concentration and might lose it".

I could probably see an argument for making this a 1st level spell. It's not only a "worse Stoneskin", it's in many situation a worse Blade Ward and that one's a cantrip and generally considered "not very good".

Blade Ward still grants Resistance against all 3 types compared to just one from this spell, and it has the same range (that is; self). It usually has shorter duration (1 round vs concentration up to 1 minute) but really that's only shorter if you don't lose your concentration the first time you get hit. Which is a big risk.

But the biggest drawback to this spell is that being Resistant to one damage type and Vulnerable to another is only useful if there's only one damage type in the battle. And that will come up rarely, in any other situation this spell is a huge liability.

I can see the Stiff variant seeing some use in ranged battles, since most of those attacks deal Piercing damage, but in melee most groups of creatures will have a mix of damage types and even single creatures with multi-attack often deal 2 or more types.

If I were a Wizard, I might have this in my spellbook if I got it for free, and I might prepare it if I knew I was going to be encountering an awful lot of a specific damage type. If I were a Sorcerer or anyone with known spells, I would almost certainly not bother with it.

  • \$\begingroup\$ I completely forgot about Blade Ward. Thanks for the response, I'm starting to see the problems with the spell now. Maybe I'll rework it and try again some other time \$\endgroup\$
    – Rokkema
    Sep 22, 2021 at 22:28
  • 2
    \$\begingroup\$ The problem with blade ward is you have to keep casting it. This spell would at least let you do something else the next round. \$\endgroup\$
    – Tiger Guy
    Sep 22, 2021 at 22:52
  • \$\begingroup\$ Some changes I thought about, besides the obvious, were allowing the caster to buff other party members, maybe even at range. I also thought that maybe it would be nice to let the buffed character change the Exterior option as a bonus action, that way it the player could think more tactically about it. \$\endgroup\$
    – Rokkema
    Sep 22, 2021 at 23:24
  • 4
    \$\begingroup\$ Note that allowing casting it on other creatures is tricky. You would probably have to limit it to willing creatures, or else it becomes a way to give enemies vulnerability. (Alternatively, make that part of the spell, give them a save to resist it, and re-balance the spell and its level accordingly.) \$\endgroup\$ Sep 23, 2021 at 3:38
  • 1
    \$\begingroup\$ Also note Protection from Energy, a third level covers one of five five (arguably less common) types of damage with the range and duration of Stoneskin. \$\endgroup\$ Sep 23, 2021 at 21:38

Trading resistance for vulnerability is not balance.

Even ignoring the deal-breaker issue with having concentration on a spell that specifically intends you to take damage, it's important to realize that mathematically, vulnerability is significantly stronger than resistance. Gaining a vulnerability is almost always a losing game to play, even if you gain some kind of resistance alongside it.

For example, suppose you're about to take two attacks that deal 10 points each, one piercing and one bludgeoning. If you do nothing, you'll take a total of 20 points of damage.

If you cast this spell with the appropriate option, you can halve the damage of one hit, reducing it to 5, while the other gets doubled to 20, for a total of 25 damage. You're actually worse off than not casting the spell at all!

  • \$\begingroup\$ This is a really important point, I was considering whether this could be used offensively if it had a range of touch, but giving vulnerability on a concentration spell sounds really broken, and if you think of it like that, why would you ever cast it on yourself? \$\endgroup\$
    – Phil
    Sep 23, 2021 at 14:10
  • 4
    \$\begingroup\$ @Phil You would cast it in any and all scenarios where you know the enemy can't capitalize on your newfound vulnerability \$\endgroup\$ Sep 23, 2021 at 14:40
  • 1
    \$\begingroup\$ @Medix2 I agree in principle, but I'm rarely that sure going into combat of anything (probably speaks to my groups playstyle). Also I can't think offhand of many monsters that only have one of Bludgeoning, Slashing and Piercing, and those that I can think of are low level enough that even a second level spell slot would be quite a heavy investment (Although I'm sure there is a comprehensive list out there that would prove me wrong). So it seems a very niche spell that I wouldn't see myself preparing. \$\endgroup\$
    – Phil
    Sep 23, 2021 at 15:42
  • 2
    \$\begingroup\$ Adding a weakness of your choice to a benefit of your choice is not balance if you can choose when you do this either. You'd use this spell when facing a foe who deals almost entirely the damage you are resistant against, and almost none of the damage you are vulnerable. The cost is really having it prepared. \$\endgroup\$
    – Yakk
    Sep 23, 2021 at 18:58
  • \$\begingroup\$ Well, if you cast the actually appropriate option (the 2nd), you would be getting bludgeoning resistance and slashing vulnerability and take 15 damage in the end. As long as you are getting 1 or 2 damage types you get ahead with this, only with all 3 you might end up in scenarios where you can't benefit with this. \$\endgroup\$ Sep 24, 2021 at 9:02

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