Ruined King: A League of Legends Story

I tried to avoid potential spoilers, that's why i didn't mention it, but i guess this is rather pointless on a site focussing on cheevos. It is the Pickpocket, it's the one that is listed directly right to Captain Thorne on page 5.
I searched for a complete bestiary online and most "game guide" sites do not have a complete list (but most of those "guide" sites are nothing more than the usual copy-paste articles from ingame sources that "claim" to explain stuff). Only nintendosmash has a full bestiary, which i used to search for the ones i was missing.

Also, i need to correct myself a little regarding the final boss:
It does not clone your active team on every KO. It is, in fact, a skill called "Destruction" that places a "doom" type debuff on one party member. I tried yesterday, and it's pretty hard to get it to use the debuff 3 times in a battle and once per party member, so it still might be easier to just alternate teams and fight twice.

@Vyrrep I take no credit for this, just used this guide to look for ones that I was missing. NEOSEEKER does some good guides as used them before for other games

https://www.neoseeker.com/ruined-king/Collectibles_and_Other...

I managed to get 5 entries on last boss, when I loaded back in after credits. I took Ahri the only bestiary entry I didn’t have out of the team and re-fought the boss. Getting Ahri in second phase in fight.
Meaning no need for second playthrough

Just a few additional tips from my side (I don't have the achievement yet, because i failed at bullet point 2 below, i'm in my second run through atm):
* As far as i know, it's very hard to miss side quests themselves, because of the vendor that sells rumors. So although optional, they are hard to miss if one regularly checks the Rumormonger and finishes them before further progressing the main story.
* There is one optional fight in a side quest and it's pretty much at the beginning of the game: It is in the Fleet Street area, atop a bridge where you'll be given the option to either fight or pay a "fee". If you chose to pay, that fight/enemy becomes absolutely inaccessible for that playthrough.
* For the final boss, i've had 5 of the 6 entries from one fight. Maybe it was linked to game difficulty, but i saw that the boss is also able to "clone" team members that it ko'd. So, if you want to save one fight, have the boss ko one member, beat the clone, rinse and repeat with the next. Might be a bit faster than to go through the entire end game sequence and cutscenes again. - Note: not necessarily easier nor faster, see my second comment below.

I think they removed the Pickpocket from the Bestiary, so anyone who missed that should try loading up the game and checking. When getting towards the end of the game, I compared my list to the Neoseeker list, and I noticed that I was missing Pickpocket (even though I'm 100% sure I killed him, I knew he was missable). But I also had 1 fewer slot for monsters than the Neoseeker list. In the end, I got the achievement, but still no Pickpocket anywhere on my Bestiary list.