In my opinion we need something like 15-20s invincible status ( or till our first attack) after death, there are a lot of situations where someone PKd me from back and after I get bavk he instantly kill me again and again. This does not have sense I should be protected for 15-20s or until my first attack to avoid these situations.

This is literately how it works currently. If you revive in the safe zone, you are protected for a few seconds or until you attack.

so you can run around for 10 sec grab the guy while invi and 1shot him in return?

id rather have something else:

Ofc they will never do it still:

like V but when you revive same everything but you can loot and talk to npc's.

Yea but in current state I cant even change channel after using elions, because guy will non stop killing me with 20% HP it does not have sense. It can be improved, by silence in this 15s. 

The same practice can also be used against you. This is definetly not a good idea.

If I was a griefer I'd KS mobs knowing I have temporary invulnerabality, if I was the invader and died intentionally.

No you will not have this possibility, because with my suggestion you would lose "protection bubble" with your first attack. Its only to let player after lost fight chance to change channel without teleporting to safe spot and running to spot again..

until first landed grab, ha? :D

Yea I was thinking about this in the end better would be silencein this 10-15 sec period = you cant use skills.

There is no need for that grace period. If you use an elions, then you know you're respawning in the combat zone. Even then you have a few momenzs before you can be killed again. 
If you respawn node, you cannot be attacked for a while until you move/ take out your weapon etc. This lets you have enough time to swap servers. In almost all cases, respawning node is a viable option because you lose nothing when the opponent kills you (except elixirs / time which you lose even with an elions) so choosing the node respawn option is the best way. 
In aakman / hystria, this spawns you outside. However, getting back inside these dungeons has been made ever easier, and with tagged classes you don't even have to worry much about buffs running out any more. 
I don't really see a need for this suggestion, as the positives are already a game mechanic to some degree, while the negatives are enabling griefing even more. 

Not in Hystria or Aakman as example I am just kicked outisde and I must looking for another teleport ☹️ Kinda annoying I am ok with being pkee killed/lose fight for spot I will just change channel and tbh this is all about. Everything can be balanced and improved. Also situations where someone after death in pvp can just stand up and "nothing happend" are dumb and should asap rethinked but its another topic