Based on the text for the Delay talent, the chance to proc is whenever the sorcerer deals damage. So let’s say I hit the other team with his Fireball skill. Does the DOT component also have a chance to proc the Delay talent’s effect?
I guess a more general way of asking this question would be to consider some of the other sorcerers with a DOT component to their special skills (e.g. Lady Locke, Rumpelstiltskin, Morgan Le Fay). I assume the behavior would be consistent across heroes, and I imagine the 5*s may have more play time with talents than a 3*.