Is Endemic from Shadow imbuement considered damage over time?
It shouldn’t be. I think they just got the old bitter infection and placed it there as a choice. I’m almost certain it counts as a damage tick so it can crit. I’m not sure if it can proc lucky hit. Before the expansion, I would run it as victimize would proc off of bitter infection ticks and all other lucky hits to do x damage. That was the only way I could get shadow dok to work for the end game.
I used the Bitter Infection aspect in S7 due to the witch power that exploded on crits. That was a ways back so it may have changed since then.
If your question is, does it get affected by damage over time modifiers, then no. It’s completely useless as a talent and there is 0 reason to use it over the shadow clone proc.