When is a skill's damage calculated?

Zhorix

Hey,

I have a question about when a skills damage is calculated. In other words, if this is dynamic or static?
Scenario: I cast magicka detonation with 2.5k spellpower on my dw bar, then change to my restobar with slightly less spellpower and remain on this bar untill the detonation goes off. Is the damage based off of my stats when casting the ability or when it detonates? And same with DOTs. can you "snapshot" the damage or does it automatically "update" the tick damage whenever your stats changes?

(Disclaimer: Yes I am too lazy and impatient to do any extensive testing myself if someone already know the answer)

Thanks in advance!