The achievement list for Bluehole's realtime MMO TERA incorporates a few achievements for levelling up, using the highest being level 65. You can make progress towards all these level achievements much shorter the other day as a double XP event is going to kick off.
Players can earn double XP for defeating monsters in dungeons along with the open world too. The double XP will stack together with the XP bonus you already receive from Elite status.
The Double XP event for TERA will commence at 6AM PDT (13:00 UTC) on July 13th and finishes on Monday, July 16th at 11:59PM PDT (07:00 UTC on Tuesday, July 17th).
We've got the entire list of TERA achievements - examine the list for guides to unlocking them.