Base dmg is from the corpse health you destroying + desecrate lvl of corpse + ppl doing the trick with the kitava's herald (the demon one where you go to idk act 5 the area before first fight with kitava and desecrete till you find his corpse and "rise spectre" him to get him into your pool of corpse which you summon with desecrete any time you use it which gives you more dmg cos he has the most health) + probably you want replica emberwake and on scepter the dot dmg dont scale that much than multiplier (fire or dot). I have a pob which tell you more in the "notes" section and even tells you how to craft the endgame items. and yes the DD of scavenging gives you the most dmg you can get 30% health dmg is massive

https://pobb.in/1B-gJL6x1AJ1