Here is the full list of all 100 Lightseekers achievements.
Defeat the Final Boss of a Campaign with a Dread Hero
Earn 100 Achievements
Win 5 Ranked Games
Reach Nature level 20
Defeat the Final Boss of a Campaign with a Nature Hero
Defeat the Final Boss of a Campaign with a Tech Hero
Reach level 100
Reach Astral level 20
Reach Storm level 10
Complete 1 Campaign
Defeat the Final Boss of a Campaign with a Mountain Hero
Reach Dread level 10
Win 1 Ranked Game
Reach Astral level 5
Reach Astral level 10
Reach Dread level 5
Reach Mountain level 5
Reach Mountain level 10
Reach Nature level 5
Reach Nature level 10
Win 1 game without defending
Win 1 game with 7 buffs on the board
Win 1 game with 35 health remaining
Win 1 game with no cards left in your deck
Play 1 Game
Play 3 Games
Play 5 Games
Play 10 Games
Win 1 game with 1 health remaining
Win 1 Game
Win 5 Games
Win 10 Games
Win 100 Games
Win 1 game without attacking
Earn 50 Achievements
Reach level 5
Reach level 10
Reach level 20
Reach level 30
Reach level 40
Reach level 50
Reach level 75
Reach Storm level 5
Reach Tech level 5
Reach Tech level 10
Reach Tech level 20
Play 20 Unaligned Cards
Play 100 Unaligned Cards
Complete 5 Campaigns
Complete 10 Campaigns
Complete 25 Campaigns
Complete 50 Campaigns
Complete 75 Campaigns
Complete 100 Campaigns
Complete 250 Campaigns
Complete 500 Campaigns
Defeat the Final Boss of a Campaign with an Astral Hero
Defeat the Final Boss of a Campaign with a Storm Hero
Defeat a Campaign Boss as the same hero
Defeat the Final Boss of a Campaign with 35 health remaining
Complete 5 different Campaigns
Complete 10 different Campaigns
Reach Dread level 20
Reach Dread level 50
Reach Mountain level 20
Reach Mountain level 50
Reach Nature level 50
Win 1 game with 0 health remaining
Defeat 5 Different Hero Challengers
Defeat 10 Different Hero Challengers
Defeat 15 Different Hero Challengers
Win 10 Ranked Games
Win 100 Ranked Games
Win 1000 Ranked Games
Win 10000 Ranked Games
Win 1 game with no cards in your discard pile
Play a card from each Order in 1 game
Defeat 1 Hero Challenger
Defeat 5 Hero Challengers
Defeat 10 Hero Challengers
Defeat 25 Hero Challengers
Defeat 50 Hero Challengers
Defeat 75 Hero Challengers
Defeat 100 Hero Challengers
Win 1000 Games
Win 10000 Games
Win 1 game without buffing
Reach level 20 in all Orders
Reach level 50 in all Orders
Reach level 200
Reach level 300
Reach level 400
Reach level 500
Reach Storm level 20
Reach Storm level 50
Reach Tech level 50
Win 1 game with only playing Unaligned cards
Play 1000 Unaligned Cards
Play 10000 Unaligned Cards
Reach Astral level 50