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