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