Here is the full list of all 24 ROUNDS achievements.
The base game contains 11 achievements, and there is 1 DLC pack containing 13 achievements.
Win 10 rounds by your opponent falling out
Win 20 matches
Use Frost Slam 20 times
Win 50 Matches
Use Demonic Pact 3 times in a single match
Use Remote 3 times in a single match
Use Teleport 3 times in a single match
Use Supernova 3 times in a single match
Lose 0-5
Use Radiance 3 times in a single match
Use Phoenix
Trigger a block with Shields Up
Use Saw