Warehouse Keeper's Pastime
2) Visit Hunters Village and talk to Warehouse Chief Baxt. He will give you the list of mobs that drop the medals, it's quite extensive. Rotting golem, gigantic monster eye, konzur bat, konzur bat lord , tulben, hunter gargoyle, dragon bearer chief, dragon bearer warrior,dragon beaer archer, dustwind gargoyle, thunder wyrm, carinkan, weird drake, grave guard, cadeine, sanhidro, connabi, bartal, luminun, innersen, nightmare guide, nightmare keeper, nightmare lord.
Here are a few I've come across so far, these are just outside of Oren town and Oren castle, group mobs around level 56.
You can start betting with 10 medals and if you do 100 you can win something better, so he says. Once you get enough to bet you can go back to either warehouse man and play. It's exactly like the infernium ore quest, for anyone familiar with that.
I've played about 20 times so far and won 3 times. Unlike the infernium ore quest, there are no different levels of winning, this is all three lines or nothing.