Return of Reckoning

Curious how this tactic functions given that it doesn't show up in combat log.

A.) Does it apply to DoTs?
B.) If yes, is it the first tick or every tick of said DoT?
C.) Is there a hidden CD on it's proc?

Thanks for any info.

Works on direct damage only, not on dots.

The archmage version is worded better.

Much appreciated, thanks for the replies!