D&D 5E Can you use Tempest Domain cleric Destructive wrath CD after you roll

[ECMO3]

Tempest domain cleric channel Divinity: Destructive Wrath.
Starting at 2nd level, you can use your Channel Divinity to wield the power of the storm with unchecked ferocity.
When you roll lightning or thunder damage, you can use your Channel Divinity to deal maximum damage, instead of rolling.


The "instead of rolling" implies this is a decision that must be made before you roll dice. Correct?

 

[Swarmkeeper]

Yes

(ETA: noticing your thread title and initial post ask the opposite questions…. So yes means you decide to do max damage and you simply don’t roll)

 

[Paul Farquhar]

I agree. Which means that "do +1d6 you roll spell damage" type abilities don't work with this ability, since you don't roll damage.