Do dmg absorption from Maiven’s /arcanist/ and Possession /occultist/ stack? will having both of them active result in 32% dmg absorption?
this would be nice 
It stacks but it’s multiplicative, not additive.
could you please explain it taking a round 100 dmg as an example?
X=1-(1-a)*(1-b) *100%
You’d end up with 70.4 damage there or 29.6% absorption. When they are multiplicative instead of adding them together the two multipliers are being applied separately.
100 x .8 (1 - 20% maivens) x .88 (1- 12% possession) = 70.4
That being I think there is rarely any point to stacking them If I was gonna use both I would likely max possession and then 2-3 point maivens
Maths. Not my thing. Thank you guys 
Yeah TomoDak 3 points Maiven’s is the best thing. 10% less incoming damage for virtually no skill points investment! 
Stacking absorption is the (sadly) only thing that makes ground damage less annoying. I have to admit I maxed both maivens and possession on a warlock just to get this effect once.
Not really, high HP regen works even better for ground and DoT dmg.
To offset the average aether ground effect you need a constant 2k regen, or more. Depends a bit on your hp, more is worse in this case. I guess you can get this much regen but it requires you to build for it, for example you will need tree of life for this. Taking a couple of skills leaves more room for your own build. YMMV.
Half of that is more than enough and no you dont need ToLs healing rain, unless you are planing to spend few hours doing noting in the middle of it.
Just 2k?
Neato! What is the base regeneration on this character? Are you wearing like 10 Earthward items or something?