Here is the full list of all 51 Pyre achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Complete a Rite against another mortal (Versus Mode)
Prevail using Rukey, Barker, and Dalbert (Versus Mode)
Prevail at the Isle of Khaylmer using Ti'zo and Messenger Imp (Versus Mode)
Prevail using Sandra, Tamitha, and Udmildhe (Versus Mode)
Prevail using Volfred, Ti'zo, and Oralech (Versus Mode)
Prevail against a Master CPU opponent with six or more Titan Stars active (Versus Mode with default Masteries, Talismans, Pyre Health)
Prevail in a Rite against a CPU opponent while you have less than 10 Pyre Health (Versus Mode with default Masteries, Talismans, Pyre Health)
Prevail in a Rite against a Master-level CPU opponent (Versus Mode, default Talismans and Masteries)
Complete a Rite against a CPU opponent (Versus Mode)
Complete your quest for freedom (Campaign)
Prevail in a Rite at each of the Celestial Landmarks (Campaign)
Prevail in a Rite against each of the other triumvirates (Campaign)
Prevail in a Rite in no more than three dousings (Campaign)
During a Rite, douse the adversary's Pyre by 40 health or more (Campaign)
Prevail in a Rite with 12 Titan Stars active (Campaign)
Using Volfred, deal 200 Pyre Damage (Campaign)
During a Rite, banish three adversaries with a single Aura Cast (Campaign)
Liberate any three exiles from your party (Campaign)
Spend 1,000 Sol in the Slugmarket (Campaign)
Prevail in a Rite with six or more Titan Stars active (Campaign)
Complete three Feats of Glory (Campaign)
Do Vocations 10 times (Campaign)
Unlock every chapter in the Book of Rites (Campaign)
Find an exile for each of the different masks (Campaign)
Achieve Rank 5 with any exile (Campaign)
Suffer defeat in a Liberation Rite (Campaign)
Using Bertrude, deal 200 Pyre Damage (Campaign)
Check 50 different pages in the Book of Rites (Campaign)
While flying, interact with 10 different observation points (Campaign)
Prevail in a Rite with three or more Titan Stars active (Campaign)
Using Pamitha, deal 200 Pyre Damage (Campaign)
Initiate 20 different conversations in the blackgwagon (Campaign)
Complete five Scribe Trials in the Beyonder Crystal (Campaign)
While flying, bump into five different adversaries' wagons (Campaign)
Prevail in a Rite using Jodariel and Pamitha (Campaign)
Using Sir Gilman, deal 200 Pyre Damage (Campaign)
Using Ti'zo, deal 200 Pyre Damage (Campaign)
Prevail in a Liberation Rite (Campaign)
Use Scribe Snuff to reset an exile's Masteries (Campaign)
Upgrade a Talisman to Rank 20 (Campaign)
Complete two Scribe Trials in the Beyonder Crystal (Campaign)
Using Rukey, deal 200 Pyre Damage (Campaign)
Using the Stowaway, deal 200 Pyre Damage (Campaign)
Using Jodariel, deal 200 Pyre Damage (Campaign)
Using Hedwyn, deal 200 Pyre Damage (Campaign)
Complete a Practice Rite in the Beyonder Crystal (Campaign)
Prevail in a Rite without your Pyre taking damage (Campaign)
Use the White Lute to play a tune (Campaign)
Begin your quest for freedom (Campaign)
During a Rite, fling the Orb at an adversary, then banish them within two sec. (Campaign)
Complete your quest for freedom (Campaign, True Nightwing difficulty)