So i have both DC and Epi on my bar.
If im fighting one target or want to lower the CD on DT a bit I use DC.
If im fighting literally more than 1 target Epi replaces it.
Both gain Sudden Doom procs so its up to the user to determine what to use based on the situation.
TLDR: 1 Target DC, 2 or more Epi.
EDIT: Uh DKs have whats called “Quadratic Scaling”. All that means is the more enemies in a pack or a pull the more damage we do. And Epidemic is what you use with that.
As far as placing Festering everywhere you dont really need to unless youre doing a very particular build.
Drop your AOE and when you pop a wound everyone in that takes some of the damage.
So Against multiple targets: Outbreak (cast another if some more join)Festering wounds on one up till about 4, DND, then SS to pop. Use Epi when youre about to cap on Runic Power.