level of mobs does not have anything to do with how often the coins drops. what does matter is DPS. if you kill slowly (ie, you're a melee type) you'll get coins slowly and vise versa. coin drop is totaly random, but the faster you kill, the more coins you'll have.
i haven't checked in a while, but i think the quest tab shows all of the mobs that drop coins.
Gold Wyvern: Doom Knight - Cemetary
Silver Unicorn: Something of Splendor - Valley Of Saints
I've been using the guide on lineage 2 stratics (really useful site btw, spend alot of time there)
I really need blood medusas atm. Do you know if level difference affects the quest drops? As in, can I take my 61 WL and pole the Timak Orcs to extincition and expect a sizeable reward in coins? or do I have no chance as they are all deep blue to me?
the coins will still drop if you go poling Timaks as it's a quest item. probably at the same rate as they were white to you
True, the coins will still drop but I personally found the drop rate slightly less than on non-blue mobs. Then again, it is all random so it could just be a streak of bad luck.
I too have a difficult time getting the blood medusas. As far as poling the Timak Orcs to get them - let me know how that goes. I did get two off of the Hatar Hanishee in two buff rounds. Might be better to just set up shop instead of hunting dark blue mobs in the hopes of getting 2-3 coins. But if it works out - great!!!
Also, new C5 mobs drop coins as well, in addition to some older mobs.
If you go to Ancient Battleground, the Skeleton Groups will drop Silver Unicorns, and the two higher level groups drop Silver unicorns and blood medusas.
I have heard that mobs in VOS also drop coins now, but have no confirmation on this, since I don't play a nuker.