I’ve never seen an llynav on life steel but I don’t think it’s really good on her.with just Elbris you have a 15% chance to counter when enemy hit Allies not including you. Since illnav is very rng reliant you’ll need to counter more. Once all your teammates die your can’t counter anymore and if she’s slow she’s going to die. Only 1.64 of people use life steel in comparison to 18.35 for counter 

I've tried lifesteal ilynav. Once they notice they'll start attacking you because she can easily die over time. She's gonna be more stat hungry than counter and speed so it might be worse for you to gear.

I don't think it was necessarily bad though. I just couldn't get her to her full potential.

If you want her bc you like the character itself then anything that you test and like will be a good build but if you want a strong one then I would recommend to keep the counter set and use her for defense teams only bc by my experience, the rng is more generous to AI than to players (rise of skynet,. I'm sure of it) or just abandon her completely bc she's hard to build and even harder to work. 

 The LS set is good if the character is able to do high enough damage (more damage = more healing). Also, it is desirable to have some kind of survival ability that makes killing him / her not an easy task (for example, Violet, S. Tene, ML Celine, etc.).

 Without Elbris and good SPD(or counter set), Ilynav will hardly do damage at all, so the LS set is practically useless for her.

 In general, despite the fact that I like this heroine, it is not easy for her to find application in pvp. In pve, it can be used as a crit dmg buffer ... but by and large its usefulness is also questionable.

 If you are a new player - I would not recommend building it, you can find many other characters that will be more useful for promoting your account.

It all depends on your playstyle. On LS, you're going for a slower style, while others would be for more "quick 'n' dirty" fights. 

I've been running her on LS /  Elbris. She's fine on LS if you can get enough stats and have the right combo of team and/or artifact. As mentioned by others, she'll get focused in RTA if they realize she's on LS/Elbris, but usually by then they're in a pickle of picking whether to deal w/ her or deal w/ another threat. I usually pair her w/ a dual-attacker or CR pusher to make sure she gets enough rotation. 

I would say she's good, but can't really be the main focus of your dmg if she's on LS. On LS she's there to support the rest of the team, injure the enemy, and be a general nuisance b/c of sticking around. Counter works on the same concept, but adds the punishment of possibly hitting back if she's hit, but w/o the benefit of the sustain of a LS set. She's not a dps going for the kill herself.