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 your quest for freedom (Campaign, True Nightwing difficulty)
Using Volfred, deal 200 Pyre Damage (Campaign)
Prevail in a Rite against each of the other triumvirates (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 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)
Complete a Rite against a CPU opponent (Versus Mode)
Prevail using Rukey, Barker, and Dalbert (Versus Mode)
Prevail against a Master CPU opponent with six or more Titan Stars active (Versus Mode with default Masteries, Talismans, Pyre Health)
Complete a Rite against another mortal (Versus Mode)
Prevail in a Rite against a Master-level CPU opponent (Versus Mode, default Talismans and Masteries)
Complete your quest for freedom (Campaign)
Using Bertrude, deal 200 Pyre Damage (Campaign)
Prevail in a Rite with 12 Titan Stars active (Campaign)
Achieve Rank 5 with any exile (Campaign)
Liberate any three exiles from your party (Campaign)
Spend 1,000 Sol in the Slugmarket (Campaign)
Using Sir Gilman, deal 200 Pyre Damage (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)
Unlock every chapter in the Book of Rites (Campaign)
Find an exile for each of the different masks (Campaign)
Do Vocations 10 times (Campaign)
Complete three Feats of Glory (Campaign)
While flying, bump into five different adversaries' wagons (Campaign)
Prevail in a Rite with six or more Titan Stars active (Campaign)
Prevail in a Rite at each of the Celestial Landmarks (Campaign)
Use Scribe Snuff to reset an exile's Masteries (Campaign)
While flying, interact with 10 different observation points (Campaign)
Check 50 different pages in the Book of Rites (Campaign)
Prevail in a Liberation Rite (Campaign)
Prevail in a Rite with three or more Titan Stars active (Campaign)
Using Pamitha, deal 200 Pyre Damage (Campaign)
Complete five Scribe Trials in the Beyonder Crystal (Campaign)
Using Ti'zo, deal 200 Pyre Damage (Campaign)
Upgrade a Talisman to Rank 20 (Campaign)
Initiate 20 different conversations in the blackgwagon (Campaign)
Suffer defeat in a Liberation Rite (Campaign)
Using the Stowaway, deal 200 Pyre Damage (Campaign)
Prevail in a Rite using Jodariel and Pamitha (Campaign)
During a Rite, banish three adversaries with a single Aura Cast (Campaign)
Complete two Scribe Trials in the Beyonder Crystal (Campaign)
Using Jodariel, deal 200 Pyre Damage (Campaign)
Using Rukey, deal 200 Pyre Damage (Campaign)
Using Hedwyn, deal 200 Pyre Damage (Campaign)
Complete a Practice Rite in the Beyonder Crystal (Campaign)
Use the White Lute to play a tune (Campaign)
During a Rite, fling the Orb at an adversary, then banish them within two sec. (Campaign)
Prevail in a Rite without your Pyre taking damage (Campaign)
Begin your quest for freedom (Campaign)