Here is the full list of all 15 Arena Stars achievements.
Earn 10 Keys.
Earn 250 Keys.
Earn 1,000 Keys.
Win a match.
Win 50 matches.
Win 100 matches.
Upgrade cards 3 times.
Upgrade cards 50 times.
Upgrade cards 100 times.
Earn 500 Trophies.
Earn 1,500 Trophies.
Earn 2,500 Trophies.
Earn 50 XP.
Earn 2,500 XP.
Earn 5,000 XP.