Lineage II/Coin of Magic

Getting the Quest
To start this quest off, you must talk to Warehouse Keeper Sorint (Northwest side of Hunter's Village). Once you accept the quest, Sorint will send you to the Union President Bernard (Center of the Hunter's Village between the two bridges) to get the Kaldis Gold Dragon Coin for him. Bernard will tell you that he does not have the coin. After talking to Bernard, you must head southeast to near the Angel Waterfall. You will get the Kaldis Coin after killing a couple of Harit Lizardmen Matriarchs or Harit Lizardmen Shamans. This monster will be around the road just slightly west of the Angel Waterfall. They are also easily found on the peninsula that is surrounded by the river in the Forest of Mirrors. Be careful of this monster. It is level 55 and aggressive. It might be best to get a few friends to help you kill it. You must get the last hit on the monster though to get the coin. Once you have the coin, go back and talk to  Warehouse Keeper Sorint. DO NOT TALK TO UNION PRESIDENT BERNARD WHEN YOU GET THE COIN. He will give you a small amount of adena for the coin and all your work will have been for nothing. Once you talk to Sorint, go through all the talk and you should find yourself a Level 3 Member of their Coin Collecting Guild. Now you will be able to collect coins which can be exchanged for better coins and then exchange those coins for reward items. To see the list of items you will be able to redeem the coins for, talk to Warehouse Keeper Sorint.

Getting the Coins
There are three types of coins that you can receive from killing monsters. All three are the lowest coins and certain amounts of these must be exchanged to certain people for better coins if you want to receive items. Here is a list of coins that drop off monsters and what monsters will drop:

Silver Unicorn Coins

 * Formor : Level 45 Passive - Found around the Ivory Tower.
 * Formor Elder : Level 46 Passive - Found around of the Ivory Tower.
 * Tarlk Bugbearn High Warrior : Level 48 Passive - Found North of Ivory Tower.
 * Vanor Silenos Shaman : Level 49 Passive - Found West of the Tower of Aden.
 * Oel Mahum : Level 53 aggressive - Found South and West by the Border Outpost.
 * Oel Mahum Warrior : Level 54 Passive - Found South and West by the Border Outpost.

Gold Wyvern Coins

 * Timak Orc : Level 40 Passive - Found slightly east of Oren Castle just past the river.
 * Shackle : Level 45 Aggressive - Found in the circle of the Ivory Tower and at the Eastern entrance of Death Pass.
 * Headless Knight : Level 50 Aggressive - Found in the West area of the Dragon Valley.
 * Royal Cave Servant : Level 51 Passive - Found in the central and West in Dragon Valley.
 * Malruk Succubus Turen : Level 56 Passive - central and East in the Dragon Valley.
 * Doom Knight : Level 65 Aggressive - Found north and south east of the Devastated Castle and at the Forbidden Gateway.

Blood Medusa Coins

 * Timak Orc Archer : Level 41 Passive - Found around the Catacomb of the Apostate
 * Timak Orc Soldier : Level 42 Aggressive - Found around the Catacomb of the Apostate
 * Timak Orc Shaman : Level 44 Passive - Found around the Catacomb of the Apostate
 * Lakin : Level 44 Passive - Found around the Catacomb of the forbidden path.
 * Hatar Hanishee : Level 49 Passive - Found East of the Town of Aden along the cliff.
 * Punishment of the Undead : Level 53 Passive - Found on Cemetery east of Aden.
 * Grave Lich : Level 57 Passive - Found south and south west of the Devastated Castle.

Trading the Coins
Here is also a list of people who you are able to exchange coins with, though many will only exchange coins with you are a level 2 or level 1 member of the Coin Collector's Guild (level 3 members are lowest and Level 1 members are highest):

Level 3 Trading
Magister Page: Southwest side of Hunter's Village (Elven Mage Trainer). He will trade: Researcher Lorain: Entrance to Cruma Tower Warehouse Keeper Hagger: East side of Oren
 * Gold Knight = 10 Gold Wyverns
 * Silver Fairy = 10 Silver Unicorns
 * Blood Werewolf = 10 Blood Medusas
 * Nia's Blood Medusa = 20 Blood Medusas
 * Gold Knight = 10 Gold Wyverns
 * Silver Golem = 10 Silver Unicorns
 * Blood DreVanul = 10 Blood Medusas
 * Nia's Gold Wyvern = 20 Gold Wyverns
 * Gold Drake = 10 Gold Wyverns
 * Silver Golem = 10 Silver Unicorns
 * Blood Werewof = 10 Blood Medusas
 * Nia's Silver Fairy = 20 Silver Unicorns

Level 2 Trading
Guard Stan: Southern Gate of Oren
 * Gold Giant = 5 Gold Drakes and 5 Gold Knights = 100 Gold Wyverns
 * Blood Basilisk = 5 Blood DreVanuls and 5 Blood Werewolves = 100 Blood Medusas
 * Silver Dryad = 5 Silver Golems and 5 Silver Fairies = 100 Silver Unicorns
 * Manak's Silver Dryad = 10 Silver Golems and 10 Silver Fairies = 200 Silver Unicorns

Trader Ralford: Shopping Area in Ivory Tower
 * Gold Wyrm = 5 Gold Drakes and 5 Gold Knights = 100 Gold Wyverns
 * Silver Dryad = 5 Silver Golems and 5 Silver Fairys = 100 Silver Unicorns
 * Silver Undine = 5 Silver Golems and 5 Silver Fairys = 100 Silver Unicorns
 * Manak's Blood Werewolf = 10 Blood Drevanuls and 10 Blood Werewolf = 200 Blood Medusas

Blacksmith Duning: Blacksmith in Hunters Village
 * Gold Giant = 5 Gold Drakes and 5 Gold Knights = 100 Gold Wyverns
 * Blood Succubus = 5 Blood Drevanuls and 5 Blood Werewolf = 100 Blood Medusas
 * Silver Undine = 5 Silver Golems and 5 Silver Fairys = 100 Silver Unicorns
 * Manak's Gold Giant = 10 Gold Drakes and 10 Gold Knights = 200 Gold Wyverns

Level 1 Trading
Head Blacksmith Ferris: Southeast side of Aden
 * Blood Dragon = 5 Blood Basilisks and 5 Blood Succubii = 1000 Blood Medusas
 * Silver Dragon = 5 Silver Undine and 5 Silver Dryads = 1000 Silver Unicorns
 * Gold Dragon = 5 Gold Giants and 5 Gold Wyrms = 1000 Gold Wyverns
 * Beleth's Blood Dragon = 10 Blood Basilisks and 10 Blood Succubii = 2000 Blood Medusas

Warehouse Keeper Collob: Southeast side of Giran
 * Blood Dragon = 5 Blood Basilisks and 5 Blood Succubii = 1000 Blood Medusas
 * Silver Dragon = 5 Silver Undine and 5 Silver Dryads = 1000 Silver Unicorns
 * Gold Dragon = 5 Gold Giants and 5 Gold Wyrms = 1000 Gold Wyverns
 * Beleth's Blood Dragon = 10 Blood Basilisks and 10 Blood Succubii = 2000 Blood Medusas

Grocer Pano: Center of Floran Village
 * Blood Dragon = 5 Blood Basilisks and 5 Blood Succubii = 1000 Blood Medusas
 * Silver Dragon = 5 Silver Undine and 5 Silver Dryads = 1000 Silver Unicorns
 * Gold Dragon = 5 Gold Giants and 5 Gold Wyrms = 1000 Gold Wyverns
 * Beleth's Blood Dragon = 10 Blood Basilisks and 10 Blood Succubii = 2000 Blood Medusas

Gambling the Coins
When exchanging coins with the NPCs, there is an option to trade less of your coins to get one of theirs, if you can guess the color of three coins that we will call coins A, B, and C. First you choose how many guesses you will get and the reward if you get it right. Then you guess what color (silver, gold, or blood) each of the three coins are (in order) and the NPC will reply with how many you got correct. You keep doing this until either you get the right combination or you run out of chances. This can only get one coin at a time, though you can only lose as many coins as you bet, not the usual 10-20 coins. Depending on the grade of coin that is being gambled, the ratio changes.

Level 3 Gambling
Gold Knights, Gold Drakes, Silver Golems, Silver Fairies, Blood DreVanuls and Blood Werewolves Nia's Gold Wyverns, Nia's Silver Fairies and Nia's Blood Medusas
 * 2 guesses cost 4 lowest coins (instead of 10)
 * 3 guesses cost 8 lowest coins
 * 4 guesses cost 9 lowest coins
 * 2 guesses cost 8 lowest coins (instead of 20)
 * 3 guesses cost 16 lowest coins
 * 4 guesses cost 18 lowest coins

Level 2 Gambling
Gold Giants, Gold Wyrms, Silver Dryads, Silver Undines, Blood Succubus, and Blood Basilisks Manak's Gold Giants, Manak's Silver Dryads and Manak's Blood Werewolves
 * 2 guesses cost 3 low coins (instead of 10)
 * 3 guesses cost 7 low coins
 * 4 guesses cost 9 low coins
 * 2 guesses cost 6 low coins (instead of 20)
 * 3 guesses cost 14 low coins
 * 9 guesses cost 18 low coins

Level 1 Gambling
Unknown at this time

Gambling tips
When gambling, it helps to know what your chances are of getting the guess right. Now, I've made some spreadsheets and tried to figure out if their were any guessing sequences that would allow 90-100% accuracy, and the closest I got was 80-85%, which is good, but you only have a savings of 10% if you get it right every time. In the following info, the letters "S", "G", and "B" stand for Silver, Gold, and Blood respectively (note: I haven't done level 2 gambling yet).

If you were to choose the "4 guesses" option, and then use the sequences SGB, BSG, and BGS (in that order!), then the following match sequences would reduce the possible answers to at most 3. The match sequences are listed as x/y/z, with x being the number of matches in the first attempt, y in the second, and z in the third, and the coin sequences is(are) the answer(s): By my calculations that will give you a 80%+ chance of getting it right every time. If you take off the 4th guess (remove the number for the z guess above), then your chances drop to more like 50% per try (ouch!). If you remove the 3rd guess (by taking off the y guess above), then it drops to around 33% (bigger ouch!). So, unless you are extremely lucky, or just have a ton of coins to burn, I would advise against gambling, since the loss % is greater than the % of coins you could potentially save. I've tried several other guessing sequences (such as SGB. BSG, and then SSS), and none were nearly as accurate as this.
 * 1/1/1 = SSS, GGG, or BBB
 * 0/1/1 = GSS or BSS
 * 1/1/0 = GSB or SBG
 * 1/0/2 = GGS
 * 0/2/0 = GSG
 * 2/0/1 = GGB
 * 0/1/0 = GBG
 * 1/0/0 = GBB
 * 0/0/1 = GBS
 * 1/2/0 = SSG
 * 2/0/2 = SGS
 * 2/1/1 = SGG
 * 2/1/0 = SSB
 * 1/0/1 = SBS
 * 2/0/0 = SBB
 * 3/0/1 = SGB (this will match first try)
 * 0/2/1 = BBG
 * 2/1/2 = BGB
 * 1/2/2 = BGG
 * 0/1/2 = BBS
 * 1/2/1 = BSB
 * 0/3/1 = BSG (this will match second try)
 * 1/0/3 = BGS (this will match third try)
 * 0/2/2 = BSS

Quest Rewards
As much fun as coin collecting is, the point of this quest is to get useful items. Top C grade items and even a C grade sword that cannot be gotten by any means other than this quest (until weapon trades via the Seven Signs event take place) are available!

Level 3 Rewards
Moonstone Earring : M.Def: 39 Nassen's Earring : M.Def: 48 Ring of Sage : M.Def: 32 Necklace of Protection : M.def: 56
 * 2 Nia's Blood Medusas = 40 Blood Medusas
 * 2 Blood DreVanuls = 20 Blood Medusas
 * 2 Gold Knights = 20 Gold Wyverns
 * 3 Gold Drakes = 30 Gold Wyverns
 * 7 Nia's Blood Medusas = 140 Blood Medusas
 * 5 Gold Knights = 50 Gold Wyverns
 * 5 Blood Dre vanuls = 50 Blood Medusas
 * 5 Silver Golems = 50 Silver Unicorns
 * 5 Nia's Gold Wyverns = 100 Gold Wyverns
 * 4 Silver Golems = 40 Silver Unicorns
 * 4 Gold Drakes = 40 Gold Wyverns
 * 4 Blood DreVanuls = 40 Blood Medusas
 * 5 Nia's Silver Fairies = 100 Silver Unicorns
 * 3 Blood DreVanuls = 30 Blood Medusas
 * 3 Silver Fairies = 30 Silver Unicorns
 * 3 Gold Knights = 30 Gold Wyverns

Level 2 Rewards
Demon Boots : P.Def: 36 Demon Stockings : P.Def: 43, MP: 117 Demon Gloves : P.Def: 36 Full Plate Helmet : P.Def 58
 * 1 Manak's Gold Giant = 200 Gold Wyverns
 * 1 Manak's Silver Dryad = 200 Silver Unicorns
 * 1 Silver Dryad = 100 Silver Unicorns
 * 1 Manak's Gold Giant = 200 Gold Wyverns
 * 1 Manak's Blood Werewolf = 200 Blood Medusas
 * 1 Gold Giant = 100 Gold Wyverns
 * 1 Gold Wyrm = 100 Gold Wyverns

Level 1 Rewards
Demon Staff : P.Atk: 152, M.Atk 111 Dark Screamer : P.Atk 122, M.Atk: 76 Widow Maker : P.Atk: 144, M.Atk: 78 Sword of Limit : P.Atk: 139, M.Atk: 76
 * 1 Beleth's Blood Dragon = 2000 Blood Medusas
 * 1 Silver Dragon = 1000 Silver Unicorns
 * 13 Gold Wyrms = 1300 Gold Wyverns
 * 1 Beleth's Gold Dragon = 2000 Gold Wyverns
 * 1 Blood Dragon = 1000 Blood Medusas
 * 1 Silver Dryad = 100 Silver Unicorns
 * 1 Gold Giant = 100 Gold Wyverns
 * 1 Beleth's Silver Dragon = 2000 Silver Unicorns
 * 1 Gold Dragon = 1000 Gold Wyverns
 * 1 Blood Succubus = 100 Blood Medusas
 * 2 Blood Basilisks = 200 Blood Medusas
 * 1 Blood Dragon = 1000 Blood Medusas
 * 1 Silver Dragon = 1000 Silver Unicorns
 * 1 Gold Dragon = 1000 Gold Wyverns
 * 1 Silver Undine = 100 Silver Unicorns

Raising your Membership Level
To attain a higher level membership, you must collect and give Warehouse Keeper Sorint certain coins.

Become a Level 2 Member
To attain level 2 member status, you must be a level 3 member and give Warehouse Keeper Sorint:
 * 1 Blood Werewolf Coin = 10 Blood Medusas
 * 1 Blood Dre Vanul Coin = 10 Blood Medusas
 * 1 Gold Drake Coin = 10 Gold Wyverns
 * 1 Gold Knight Coin = 10 Gold Wyverns
 * 1 Silver Fairy Coin = 10 Silver Unicorns
 * 1 Silver Golem Coin = 10 Silver Unicorns

Become a Level 1 Member
To attain level 1 member status, you must be a level 2 member and give Warehouse Keeper Sorint:
 * 1 Silver Dryad Coin = 100 Silver Unicorns
 * 1 Silver Undine Coin = 100 Silver Unicorns
 * 1 Blood Basilisk Coin = 100 Blood Medusas
 * 1 Blood Succubus Coin = 100 Blood Medusas
 * 1 Gold Giant Coin = 100 Gold Wyverns
 * 1 Gold Wyrm Coin = 100 Gold Wyverns

Become a Royal Member
To attain royal member status, you must be a level 1 member and also be level 55 or higher. For this you will get a new quest even more rewarding than the last!