Here is the full list of all 24 Flamebreak achievements.
Complete the Zombie's Quest.
Win 5 games in a row in Hard Mode.
Deal 50,000 damage with a single hit.
Complete the Lich's Quest.
Complete the Giant's Quest.
Complete the Halfling's Quest.
Obtain 40 favor with Furere, God of Rage
Kill Necrus, Sepicles, Halarin, Furere, and Proctus
Fight your way through the Steelclad Stronghold and slay Proctus, God of Protection
Complete the Orc's Quest.
Complete the Minotaur's Quest.
Complete the Human's Quest.
Complete the Faerie's Quest.
Complete the Elf's Quest.
Win 5 games in a row in Normal Mode.
Fight your way through the Realm of the Undead and slay Necrus, God of the Undead
Complete the Dwarf's Quest.
Complete the loot hook minigame with a perfect score twice in a single run.
Complete the treasure defense minigame without losing any treasure or allowing a single goblin to escape
Fight your way through the Grove of Renewal and slay Halarin, God of Healing
Fight your way through the Furyborn Crags and slay Furere, God of Rage
Flawless clear 3 minibosses in a single run
Fight your way through the Plane of Precipitance and slay Sepicles, God of Speed
Fight your way through the Worldfire Peaks and slay the Phoenix.