# Is a creature's Innate Spellcasting save DC affected by changing ability scores or adding Spellcasting features from another creature?

I'm creating a Svirfneblin Evil Mage by combining the stat blocks for each Evil Mage and Svirfneblin.

A Svirfneblin's Innate Spellcasting Save DC is 11 and its INT is +1. An Evil Mage's Spellcasting Save DC is 13 and its INT is +3.

I'm taking the abilities from Evil Mage and Svirfneblin and taking the higher ability scores (and modifiers), does the increased INT modifier from the Evil Mage's score affect the Innate Spellcasting spell save DC?

• – StuperUser Aug 10 at 16:55

## Yes

Spellcasting save DCs for monsters are calculated by:

$$8 + \text{Proficiency Bonus} + \text{spellcasting ability modifier}$$

If you are using the higher Intelligence score, it would also increase the spellcasting save DC.

As a side note, the Proficiency Bonus of a monster is determined by the Challenge Rating, as detailed in Chapter 12 of the Basic Rules.

• Interesting. Especially the proficiency bonus note. Once I've solved a few issues, I was going to ask about how to rebalance the CR, because there's some overlap, so not sure if it's going to be a straight addition, or how simple it would be. Now, that CR update affects its Proficiency which will affect its CR etc. – StuperUser Aug 10 at 16:57
• @StuperUser Yeah. The recommendation in the DMG is literally to guess what CR it might be, and then keep adjusting accordingly until everything matches. The CR calculation is actually quite confusing, but there are some online tools out there to help – David Coffron Aug 10 at 17:05

The suggested way to add a race to NPC is to simply add the racial features from the NPC Stat Blocks section of the Dungeon Masters' Workshop in the DMG, as per the answer to How do you add a race to a race-optional monster?

More specifically to this case, adding the Sverfneblin racial features to the Evil Mage stat block in this way doesn't change the Intelligence Ability score or INT modifier and, as the spellcasting save DC is set as per David Coffron's answer and Step 12 of Creating a Monster Stat Block:

You can determine save DCs in one of two ways.

Use the Table. You can start with the monster’s expected challenge rating and use the Monster Statistics by Challenge Rating table to determine an appropriate save DC for any effect that requires a target to make a saving throw.

Calculate the DCs. Alternatively, you can calculate a monster’s save DCs as follows: 8 + the monster’s proficiency bonus + the monster’s relevant ability modifier. You choose the ability that best applies.

There is nothing in the DMG (that I can see) that states a DC would be affected by adding Innate Spellcasting, so in this case, with no relevant ability changes, it remains the same as the base monster.

• I highly recommend doing this rather than just mashing the two stat blocks together and taking the higher number. A) it's less time consuming, and B) it's easier to balance since the adjustments are only minor and/or cosmetic. – RevenantBacon Aug 11 at 12:28