Does my skill tree make sense?? And more specific: Does my Demon Skill tree make most sense like that or no?

Chaos:
- Ofc all 3 fire skills maxed

Eldtrich:
- 1 blade warp as tele (and the 2 sk that you need for it)

Demon:
- 1 bind demon (and the skills that you need to get it)
- 10 soft sk demonic mastery --> so that I can have 2 demons: one bound demon (hephasto with convi aura) and consume a tainted for dmg and -x% enemy fr
- 11 soft sk consume --> at lvl 11 i believe the -x% enemy fire res and x% fire sk dmg are maxed out at -15%efr/+20%ed when you consume a tainted
- (?) MAX BLOOD OATH: apparently only hard sk points matter, but with lvl 20: 43% dmg taken goes to your demon, which is pretty nice and should make my wl extremely tanky, no?

there should be a couple of sk points left, which i would put into consume for added life and frw.

Makes sense??

And bonus question: is there a build that combines fire/apocalyse with echoing strike, so that you can use a high dmg weapon on swap and kill fire immunes?

well you should be getting a point in hex siphon if you aren't already, its going to offset most of the mana usage alongside an insight merc and pretty necessary for fire
you can go up to 20 soft demonic mastery (on both swaps without battle command) if you want to throw in the free 1 point defiler for a substantial damage boost and picking off stragglers, how much of an investment that is depends on your gear, its way easier with anni/torch/enigma/etc, which you probably don't have if you're using blade warp.
and indeed once a char is fully geared, besides saving 3 skill points on blade warp, a warlock can actually use a cta + splendor swap built in a +3 hex siphon build, saving him 3 skill points to get hex siphon in exchange for -1 battle orders, definitely a good tradeoff

Thanks for taking the time to respond. I don't quite see it the same way. Hex Siphon hexes your weapon and give you mana/life after each kill. however, you need to hit the enemies with your weapon, which i don't do as a fire wl. Also you need to skill it quite high with synergies to get decent ll/ml.. And tbh I dont have mana problems as my merc has insight.
Getting demonic mastery up to lvl 20 to also get a defiler doesn't seem to make sense as binding souls can be negated as I do big aoe dmg with apocalypse and consuming him helps magic builds, not fire builds.

Anyone else with some insight?

Unlike the other 2 hex buffs, hex siphon provides a global buff for +life/mana after each kill that works with any attack or spell, not just weapon attacks.
So my +38 life/mana after each kill hex siphon works for kills with blood boil, just like it does for flame wave, apocalypse, fire nova, echoing strikes etc.
It won't work for kills made by your summons / merc, however.
With +skills on items, 1 point hex siphon provides a huge source of mana gain and a significant amount of life gain, so using a skill like apocalypse can often totally refund or even refill your mana pool when otherwise its so expensive you can't cast without chugging potions, even with insight.
And you can even get hex siphon from a CTA + tome swap, having a splendor in a +3 hex siphon codex ideally.

I mean, just try it in a hero edit build if you don't believe it, the difference between a fire warlock with hex siphon and one without is huge mana issues and potion chugging vs virtually infinite mana from flame wave / apocalypse

So if I understand correctly, I put one sk into hex:siphon, cast it at the beginning of a run on my weapon and as long as the hex lasts it gives me the +l/+m after each kill. Ok, thats interesting.. I didnt know. Thanks.

its just a general buff like enchant, sticks around as you swap weapons, gives the +mana/life as long as buff is active, no extra steps required just casting the buff

What do you think about Blood Oath and Psychic Ward?

I have 1 point in psychic ward and tbh it doesn't do much. It can tank the first hit of a monster, but then its gone.. and often times I forget to cast it again.. so I'm thinking about dropping it.
However, blood oath would be dmg reduce. So if i do max blood oath + hex siphon, that should be a good combo of dmg reduce and life/mana aek..

You should max blood oath on every build since its busted. I dont bother with low psychic ward, not even worth the effort to cast if you have it. If you do take lethal damage its a dinky extra hp buffer, the rest of the time you leech back chip damage instantly from siphon but youd have to keep recasting ward

my equip gives me +7 sk, which would get Hex: Siphon to lvl 8 (with 1 hard point in it) meaning ---> +9 life / mana after each kill. Is that good enough or would you spend some extra points?