Here is the full list of all 27 Arena Hero achievements.
Defeat the slime king without attacking it.
Complete the chaotic champion's league.
Reach hero level 100.
Complete the champion's league.
Complete the chaotic gold league.
Reach hero level 80.
Complete the gold league.
Discover 80 unique items.
Reach hero level 60.
Complete the chaotic silver league.
Reach hero level 40.
Discover 60 unique items.
Complete the silver league.
Discover 40 unique items.
Bounce 3 times off the air.
Have 7 tier 3 items equipped.
Have 5 enhancers equipped.
Wear a tier 2 armor set.
Complete the chaotic bronze league.
Discover20 Unique items.
Reach hero level 20.
Defeat a Legendary enemy.
Complete a chaotic arena.
Complete the bronze league.
Defeat a boss.
Discover 10 unique items.
Defeat a champion enemy.