Need more honest info on DoT interaction with everything else

As said in the title. For example, Essence Drain would make a great synergy with Blood Mage ascendancy.
But it is impossible to find out beforehand whether nodes' and skills' wording means what it says.
I think Essence Drain DoT is Spell Damage, but I am not sure Chris and GGG think the same.
Especially how anti-fun and D4-like new changes are.