What's a good Duelist build for lvl 90 Achievement in SSF HC?

Level 90 in a Hardcore league is my only missing achievement. I have a level 86 Slayer from ages ago (but can respec the class) with 2 or 4 Lab points I'd like to respec and try to complete the achievement with. I need something safe, but at the same time something that deals enough damage to kill monsters in low/mid level maps. I plan to play very carefully in not-red tier maps until I reach level 90 before I try something more challenging, so there's no need for the build to be god tier (note I also play in SSF). I also almost don't have any new or high tier uniques. Previously I played with a 5L Chin Sol. And build ideas or guide links for me?

Thanks in advance!

I am working on this right now, funny enough.
I am just running Delve and low tire maps to get to 90.
Only 5 levels to go.

If you go here: https://poe.ninja/challengehcssf/builds you will see that top Ascendancy is Champion with 23% played. So switch to Champion.
If then you click at Champion you will see 'Toxic Rain' with 59%. So this is going to be your main skill.
If you then click on 'Toxic Rain' https://poe.ninja/challengehcssf/builds?class=Champion&skill=Toxic-Rain you will see the links you should use: Mirage Archer, Efficacy, Void Manipulation, Faster Attacks, Vicious Projectiles. You can also see that you should use a support totem link with Withering Touch.
You can also see which Ascendancy Notables you should invest in: Obviously 'Fortitude' and 'Inspirational'.
Further down you can see additional skills to use such as Determination, Defiance Banner, Malevolence, Molten Shell.
If you dont know how to make your passive you find it here: https://poe.ninja/challengehcssf/builds?class=Champion&skill=Toxic-Rain&heatmap The passive masteries to get are also shown on the left side.

Back in bestiary I played max block cyclone for this achievement, and was quite easy. Boring, but easy - with LifeOnHit counter attacks, could easily survive in the middle of beast packs for 10+ seconds, in case of lag spikes or disconnects.

Probably Delve is the most efficient safe XP out there. Second option is T1-T10 maps, you don't need to go higher then T10 for level 90. Probably T5 is good enough also.

Thanks for suggestions. I tried Exsanguinate a few leagues ago and didn't feel strong enough to survive, so I won't risk it. I have a TR char in Scourge, I guess I could give it a try if I find a bow for it, and if I level the gem. I'm not a fan of cyclone, and not sure if block works as well this league as it used to before.

Keep in mind that the Eternal achievement can be completed in any HC league, so if needed you could always migrate so as to buy any needed gear/gems.

On the other hand, I do understand the challenge of SSF!

I have two 91's still alive in SSF HC Scourge but both are witches.

A champ duelist tho is VERY viable; you could get some ideas from here as well...

https://poe.ninja/challengehcssf/builds

Good Luck!!

I know, thanks, but non-SSF HC doesn't appeal to me. Maybe I'll just wait for another league...

Did my SSFHC 90 with Necro. Doesn't get safer than that as you aren't even in the fight. Just sit back and let your minions handle it. I waited till I got 90 before I did the Uber lab.

I tried it with Necros a few times in the past. Once it was a SC try that died in Lab (....if fact it miiiight have happened more than twice). My Bloodlines Necro died due to my silly mistake. I had another together with that Duelist, but didn't have enough time to finish it... Or did this one die to a revenant monster in a map...(I didn't even know that map had revenants until I died!)? They always die to something sudden and invisible.

I'll definitely try a Necro if my Duelist dies, though. It just feels it could be faster to level from 86 to 90 than a new Necro.

Nonetheless, this is a good suggestion, thanks!