9.4.0 Frontier Coins »« 9.2.0 Ironite
9.3.0Iron coins are the primary currency used in the Arena store. While ironite and gold are also used, the most valuable purchases are done with iron coins.
The primary use for Iron Coins (IC) is relics. If you run out of relics to buy, then there are plenty of other things you can grab, but relics may ONLY be purchased with IC.