Here is the full list of all 37 TOME: Immortal Arena achievements.
Unlock a Dance for a Guardian
Win your first PvP Match
Win a match as a Tank
Win 5 Coop Vs AI Matches
Win a match as a Tactician
Win a match as a Slayer
Unlock 5 Guardians
Win your first Coop Vs AI Match
Win a match as a Pusher
Unlock 1 Guardian
Win 50 Coop Vs AI Matches
Win a 1v3 Practice Match
Win 5 PvP Matches
Win 20 PvP Matches
Win 100 PvP Matches
Win 1000 PvP Matches
Unlock a Blessing
Unlock 6 Blessings
Unlock 18 Blessings
Achieve Level 6 in all Domains
Achieve Level 6 in the Fire Domain
Achieve Level 6 in the Air Domain
Achieve Level 6 in the Water Domain
Achieve Level 6 in the Earth Domain
Achieve Level 6 in the Death Domain
Achieve Level 6 in the Creation Domain
Unlock 20 Guardians
Unlock a Relic for a Guardian
Unlock 3 Relics for a Guardian
Unlock 30 Relics
Unlock an Ascended Skin for a Guardian
Unlock 20 Ascended Skins
Achieve Harbinger Level 5
Achieve Harbinger Level 20
Achieve Harbinger Level 50
Achieve Harbinger Level 100
Complete the Beginner Tutorial