For Starters, I'm 51 Warrior/27 Monk (Galka) and I asked a lvl 73 ninja/war to help me. He said yes and we headed to palborough to egg room.
We killed it with ease and I got egg and headed back to Bastok via boat and talked to Deidogg.
Off to jeuno where i hopped a bird to Castle Oztroja. When inside i luckily found a group of 70+'s doing genkai 5, 2 of which i knew. I stood at entrance and they all went and killed leeches.. i lotted a hefty 47 and got the parasite skin.
Af2 completed in a little over an hour and a half. Fairly easy with one or two high lvls.
These coned Decent Challange to me when I went to kill them at Lv 52. Was going to try to solo, but a Lv 74 WAR from LS offered to help. So it was no problem with him ^_^ You can probably do it with a Healer the same Lv as you.
I did this tonight, and I found it easier to do it solo (died earlier in a group because invisible wore off)
first I bought a stack of prism powders (I only used 2, so bring 4-5 just incase)
then I went to the castle, got to the corridor where a lot of yagudo sentinels and such waited, so I used flee AND THEN prism powder, then I ran through, I snuck by an ooze.
I came to this room a large fountain and in the middle a bunch of yagudo parasites, I ran (flee wore off a this point) to a safe spot and waited for the powder to wear off. IT wore off so I re applied the powder. these leeches are actually agressive so I went near one of them, taking care not to let them link and got ONE's attention, I ran back to my small safe spot, and killed it (I used mighty strikes to ensure victory) and it dropped the skin, 100% drop rate.
it is IMPERITIVE that you dont let it hit you on the way back, if you do invisible will shed and you could have all those Very tough and tough yagudos on you faster then Oprah on roast beef.