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