Natural bond is for skilled players, hehe.
Not getting hit is for skilled players I would say.
“But venting my unchained” you d say. Worst option for unchained is to have NB and carry tome from the start I would say, for character, which can get downed by two random non-lethal attacks. Two backstabbing slave rats can put you on the grey screen, and you wanna be NB and carry tome? With how bad mage melee weapons are you would be hit from the front also. No, thanks, you d better take increased healing and stack yourself some temp HP for venting or gtfo.
I personally think any other trait is better.
Even if your elf eats every stormvermin overhead and drink every draught on the way, having other traits is better. As fk, ib or uc you may pass level without been need of healing cause you have 225, 216, 180 HP. You get some hits, horde is coming, you get some temp HP. What you need NB for? IDK.
As squishy 120 HP impact of every hit on you is much higher, cause more likely you are not supposed to face hordes with your melee weapon, but take care of specials with a gun. Where getting hit with 2grims is half of your HP, better be able to heal yourself and don’t duck around with NB, which most likely will cause problems not for you, but for your teams, cause they have to proceed as three after first cheesy special or ambush