Getting close to level 30 on my pure int assassin and I'm worried about how I'm going to pass the advancement quest. Any tips guys?
Get amorian baskets/maple pops (from some monsters in haunted house) for accuracy get attack pots (warrior elixer/heartstoppers) buy 100% claw for attack from the npcs (70k each) and scroll your garnier get a decent attk wg, luk robe, or even a luk cape if you can find (possibly dex face/eye accesories helps too) get some useful buffs like SE if you have (helps a tiny bit); mw is useless if your luk/dex is 4 When inside, don't bother jumping down, just work on killing one of the blue mushie and cursed eye on the first platform since it'll take you a long time to kill just one of them. If you logged off or get disconnected, you'll be warped back in kerning city and your dark marbles won't be lost, I'm not sure if this is a bug or intended to work this way, but I'll point this out so you won't be stressed out on completing it in one try.
You could ask another thief to do the job advancement together with you. You get warped into the same map even if you're not in a party. I had the same problem on my int archer and was lucky enough to have a random archer doing the job adv at the same time. Also, @Riv 's strat works too. I tried using an onyx apple + amorian basket, but by the time the apple ran out, I only had 11 marbles. Expensive job advancement...
You don't need to do the job advancement at level 30 as you won't lose any skill points for second job - if that's what you're worrying about. In fact, since I was heavily washing my Night Lord, I didn't get my second job advancement till around level 95, and then third job at somewhere around level 110.
Might be wise to get an all class melee weapon in case you run out of stars. I had to finish my job adv using a versalmas polearm.
I've recently done the advancement with my lv 30 thief in 10mins and was able to hit at least 100/100 with my lucky seven I had att27 garnier and luk20 robe. And used cider from showa and amoria basket. I can sell the garnier for 120m. pm on my inbox if you are interested
another way: hunt for houndreds of red snail shells and use the begginer skill.. its 50 dmg per hit its enough