Adventure Coins

Adventure Coins are system introduced in patch 80 in March 2019. These are not actual in-game items, but system limiting your dungeon entrances.

Previously TERA limited dungeon entrances to two for easier level 65 dungeons and to one per day for endgame dungeons (for each character). Elite/Premium subscription gave two times more daily entrances to all dungeons. Under new system dungeon entries are limited by coin cost. Non-paying players get maximum for 1000 coins. Coins reload 1 per minute. Elite players can have maximum of 1680 coins and coins reload 25% faster (4 in 3 minutes). Coins are separate for each character. You can still switch characters and play same dungeon again.

Originally lower dungeons costed 90 coins. Higher endgame dungeons and some others (like MC that gives easy leveling XP) cost 220–330. This allows even free-to-play player play highest dungeons 3 or 4 times in row. Also Adventure Coins reload fully (1000) in 17 hours. However, even new system has weekly limitation. Most dungeons have weekly limit of 40 entrances. Some, like Ghillieglade and some event dungeons still have daily limits.

After many changes in early 2022 free-to-play players have 1400 daily coins and premium players 2400. There reload fully in one day.

It's unclear what was rationale of this new system. Least it allows publisher to sell items to reload your coins in Shop for real money.