What is the DC of the Tempest Cleric's Wrath of the Storm feature?

Question

Tempest Domain clerics have the ability Wrath of the Storm (PHB, p. 62):

When a creature within 5 feet of you that you can see hits you with an attack, you can use your reaction to cause the creature to make a Dexterity saving throw. The creature takes 2d8 lightning or thunder damage (your choice) on a failed saving throw, and half as much damage on a successful one.

It doesn't specify what the DC of the saving throw is.

I assume it uses the spell save DC, even though it technically isn't a spell?

Spell save DC = 8 + your proficiency bonus + your Wisdom modifier

Answer 1

Cleric's Spell Save DC

You are correct that RAW the saving DC is not specified. I have been unable to find any source that officially corrects this oversight. However, I think using the cleric's spell save DC is a fairly safe assumption.

Most cleric features that require a save come under the Channel Divinity set of features. In the text for that feature we have:

Some Channel Divinity effects require saving throws. When you use such an effect from this class, the DC equals your cleric spell save DC.

Technically Wrath of the Storm is neither a spell nor a Channel Divinity effect so this isn't RAW. I believe we can draw an effective parallel to use this a precedent though. Additionally, wisdom is listed as the primary ability for clerics so it is a reasonable assumption to default to this when a class feature is lacking an exact definition.