There is a large variety of stones you can buy to use. These stones will differ according to maximum mob level and reliability. You get what you pay for in terms of reliability of the stones and prices may vary depending on the server you are playing on. Soul stones can be purchased at either the Ontarian or Grammarian arenas with your Aion gold. Each stone category has six sub categories or sizes. The size determines the maximum monster level the stone can hold. For example, if the biggest monster in the group you are fighting is level 180 you will need to use a stone with a minimum level of 200.
