Spell DC is a property of all spells, but usually only comes into play when the spell has a saving throw.
Spell save difficulties are not set by the Dungeon master.
Formula to calculate spell save dc 5E.
The proficiency bonus represents your experience from a role playing viewpoint, and your power curve from a game design viewpoint.
A wisdom modifier or an ability’s modifier is usually the part of the ability that is used for attack rolls, defenses, skill checks and other features of your character.
Example:
Suppose you managed a proficiency bonus of 5 and an ability multiplier of 7, calculate your spell save dc.
Therefore, your spell save dc is 20.
