Please help me understand Witch Ascendencies

HEy guys, i played basically blind into EA, having little time, just progressing very slowly in HC. I am now lewvel 29 and finished the trial of ascendency with my ES chaos dot Witch.

Finally i was able to ascend and when i saw the Blood mage and Infernalist nodes i had to reevaluate my life decisions a little bit. I had seen Infernalist a little bit in a stream, so i thought that was not the right one for me, so starting with Blood mage. Please coorect my misconceptions:

1) YOu need Sanguimancy for everything and Sanguimancy. Sanguinmancy is a debuff/malus for anyone trying to do DoTs, because while killing stuff sure does create Life Remnants, against bosses this will only work if you crit them. Which DotS don't. This node is already heavily debated in if it actually is good enough even with critting builds, for Dots in HC it is straight up suicidal.

2) Also because Vitality Siphon does not help either for Dots, as they again don't hit.

So with those two already, Blood Mage is not viable, so what is it viable for? It needs to work with hitting spells, Witch has those, they are the bone spells and in the artwork the witch is casting bone spears with her blood.

3)Gore Spike and Sunder the Flesh: Those give crit chance, crit multiplier and base crit chance for spells. Sounds good, moar damage and more sustain. Sunder the flesh, however, which sounds great, is useless for a bone witch, as the bone spells already have all 15% base crit chance. What am i missing here? Gore spike is mediocre at best, but it leads to something you will only take if you are not playing bone spells. suuuuper strange.

4) Blood Barbs. 10% more damage, nice. Elemental damage also calculates into bleeding? I mean, that sounds again like it was designed to allow Sorceress stuff to be used instead of bone spells. Why?

5) Open Sores might be nice to put an infinite decay on mobs and improve maybe hexblast? This might be super good for some builds, don't know.

6) Grasping wounds and crimpson power sound good, if you already think the rest of the ascendancy is good.

SO bascially, you get good regen and potentially a lof of life for the chance to die with 1 and 2, which you will probably always take, and then you can chose if you want good tankineyy with 6 or a little bit of crit with 3 or something with curses or elemental damage. is that really all????

Infernalist: Has some nice mitigation option with Loyal Hellhound and Altered Flesh, The Beidats' things are not working with CI, but having Health and ES might be quite good with this.

Demonic Posession sounds again like something that is cool but again soudns like something that is bad in HC, same with Grinning Immolation and Pyromantic pact nodes. Why does GGG want to murder HC Witches? These damage debuffs might be all super good tradeoffs, i would rather not want totest it though.

The third ascendancy might solve my problems, but i am also not a minion user. Really not sure what they were thinking with those, they are both super gimmicky and don't address the occult skills very much at all.