We are soon adding a small update to Combo Mastery that will help when a player receives Combo Mastery Tokens for a combo they already have at Combo Mastery level 3.
After the update, any Combo Mastery Tokens you receive for a combo you already have at maximum mastery will automatically convert to Mastery Stones (1 token = 100 Mastery Stones). We expect to add this to the game sometime next week.
If you are already holding onto extra tokens that you do not need, or acquire them before this change goes live, your extra tokens will be automatically converted and your overflow stones will be sent to you via the in-game mailbox.
If you have any questions or concerns, please contact us.