Lunar Coins are a special account-wide currency available in Risk of Rain 2, rarely dropped by enemies. They appear as giant silver coins with a blue outline and must be picked up manually via the Use key, after which they are tracked on the HUD, under Gold with a purple $ sign. Lunar Coins persist between runs, allowing for slow accumulation of large amounts.
The explosive pots around the Abandoned Aqueduct and the explosive barrels around Rallypoint Delta can also drop Lunar Coins.
They can either be redeemed at Newt Altars to gain access to The Bazaar Between Time, used at a Shrine of Order to "Sequence" all items, or used to open Lunar Pods in regular levels. In both cases, they are used to acquire unique Lunar items which grant powerful bonuses, but unlike regular items also incur significant penalties or other unusual drawbacks. Lunar Pods grant a random Lunar item for a single coin, whilst specific items may be purchased for two in the Bazaar.
10 Lunar Coins can also be used to unlock the Artificer and complete the Pause Challenge, though accessing the Bazaar requires either luck (for a random blue orb spawn) or use of a Newt Shrine/Altar for a guaranteed orb spawn (which costs another Lunar Coin). Thus, whilst playing alone, 11 Coins are needed for the Artificer unless a random orb spawns. If playing online, a teammate's portal can be used.
5 Lunar Coins are granted each time the game is ended at A Moment, Fractured in obliteration. This gives a reliable way of obtaining Lunar Coins.