Here is the full list of all 12 Ether Loop achievements.
Defeat the corruption
Survive wave 3
Defeat the molten spider
Accumulate 25 items
Accumulate 20 items
Defeat the wyvern
Survive wave 2
Accumulate 15 items
Defeat the giant centipede
Accumulate 10 items
Defeat the golem
Survive wave 1