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