What is my spell save DC?
I am a level 1 Rogue (going Assassin archetype) and have no spells.
My stats are as follows:
- STR: +1
- DEX: +3
- CON: +2
- INT: +1
- WIS: +0
- CHA: +2
If you have no spells, you have no spell save DC. Leave it blank.
Spells and spell saves are associated with a specific spellcasting class and a specific spellcasting ability. For example, if you are multiclassed as a cleric/wizard, you will have a cleric spell save DC (based on Wisdom) and a wizard spell save DC (based on Intelligence).
The feature that gives you access to spells will tell you your spellcasting ability for those spells, e.g. the Spellcasting class feature for most classes, Pact Magic for warlocks, the Magic Initiate feat, etc. Your spell save DC is equal to 8 + your proficiency modifier + your spellcasting ability modifier associated with the spell.
If the formula for calculation a spell save DC is 8 + spell casting modifier + proficiency, then the formula would spit out 8 + 0 + 2 = 10. (0 comes from not having a spellcasting ability)
Though it should (and seemingly has been in Louis Wasserman's answer) identified that this stat is pretty much irrelevant for your character as he or she is currently; if they had a spellcasting ability it would be stated in the class abilities.
If you absolutely need to put something in the box, then it seems for now 10 is a technically correct number to put there.