In DnD 5e - Does anyone know what the rationale behind making the base DC of a spell saving throw 8 instead of 10? Most attacks, passive attributes, spell attacks use 10 as the base. The average of a d20 die roll is 10.5 (rounded down would be 10).

8 seems like a very specific choice and slightly arbitary.

This information is not included in the PHB, DMG or anything as far as I can tell. Have the designers talked about it anywhere?


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    \$\begingroup\$ I'm voting to close this question as off-topic because designer intent questions have been deemed to be off-topic \$\endgroup\$ – Sdjz Oct 4 '18 at 11:50
  • \$\begingroup\$ It is easy to speculate on this though and I invite you to come into Role-playing Games Chat and ask there (for people's opinions on the subject) \$\endgroup\$ – Sdjz Oct 4 '18 at 11:52
  • \$\begingroup\$ Sorry about that. Should I delete my question or are "off topic" questions still allowed? What does "off topic" mean in the case of SE, sorry I am newish here. \$\endgroup\$ – MooseBoost Oct 4 '18 at 11:56
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    \$\begingroup\$ It is quite alright really! No need to delete the question, there is no penalty or anything for having a question closed. Off-topic simply means that the site's format is unable to answer this question in a satisfactory way, you can read more about in the help center \$\endgroup\$ – Sdjz Oct 4 '18 at 11:59
  • \$\begingroup\$ Note that there may be an alternative way to ask this question that would be on-topic if you want to edit your question: try asking what the consequences would be if you changed the base DC from 8 to 10 (or whatever). Then anybody who wants to answer your question can analyze it based on objective facts, without depending on the game's designer to know for certain. \$\endgroup\$ – Bloodcinder Oct 4 '18 at 14:42

It makes the DC for an 'average' level 1 character 10

The save DC of a spell includes the PC's proficiency bonus, as a means of scaling with levels, in the same way as attacks (that the character is proficient with, obviously). If this weren't included, spells that use saves would fall behind attacks slightly in terms of effectiveness.

Since the spells using save DCs should have a meaningful chance of both success and failure (otherwise why bother rolling), a base of 50% seems reasonable, which is ~10 for a d20 without bonuses. But since the proficiency bonus needs to be worked in and starts at +2, using 8 makes it a 10 at base.

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    \$\begingroup\$ Hello BouncyBob and welcome to RPG.stackexchange. Kindly take the tour! I'm sorry that your first answer got such a bad reception --- it's probably because we consider questions asking for designer intent to be off-topic, and answers like this where no sources are provided are essentially guesses. Your answer in particular also doesn't address the fact that if 50% is a desired number, why isn't the base value 9 instead of 8. Nevertheless, I hope this doesn't discourage you from participating further :) \$\endgroup\$ – kviiri Oct 4 '18 at 14:01

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