This achievement is awarded for killing all the Code Red Daemons. Some Daemons are hidden and require side quests to find.
1) Shrieking Demonic Bat - Hadlow Hollow: Cavern in the North Marsh
2) Rampaging Axe Wielding Ape - Danann Highway: Lifeblood of Trade (Rangetsu Initiate Side Quest)
3) Creeping Viper - Galles Lake Road: Yawning Wetlands
4) Corrupted Orb - Barona Catacombs: City Drainage System
5) Overzealous Spider - Yvolg Ruins: Forgotten Edifice
6) Winged Harbinger of Death - Brigid Ravine: Valley of Howling Winds
7) The Coming Tendrils - Vester Tunnels: Old Mining Site
8) Life Coveting Fairy - Fens of Nog: Secluded Waters
9) Mobile Man-eating Plant - Warg Forest: Emerald Labyrinth
10) Frenzied Wolf - Burnack Plateau: The Great Junction
11) Beast of Blades - East Laban Tunnel: Underground Passage (Rangetsu Initiate Side Quest)
12) Flesh-Rending Star - Maclir Beach: Thundering Southern Seas
13) Queen of the Seas - Manann Reef: Wondrous Rock Formations
14) Cannibal Mass - Palamides Temple - Southern Ruins (Rangetsu Initiate Side Quest)
15) Moon-Baying Wolf - Figahl Icecaps: Land of Dancing White
16) Rainbow Roc - Aldina Plains: Land of Vitality
17) Serial Killer Tree - Davahl Forest: Fog-Shrouded Mystery
18) Noxious Creep - Perniya Cliffside Path: Along Silent Shores
19) Consumer of Caravans - Morgana Woods: Crimson Sea of Trees
20) Untarnished Silver Corpse - Tranquil Woods: Autumn Colored Forest
21) Eater of Gold - Baird Marsh: Domain of the Old Kingdom
22) Wanton Devil - Titania: Island Prison
23) Phantom - Earthpulse: River of Nature Powers (Morgrim's Side Quest - Yseult after unlocking final dungeon)
24) Broken Malak Test Subject - Faldies Ruins: Northern Checkpoint (Hellewas Church Side Quest - Late in game)
25) Blood-Spraying Crystal - Gaiburk Ice Field: Edge of Survivability
26) Daemonblighted Noble - Vortigern: Sea Gate Fortress (Rangetsu Initiate Side Quest)
27) Deadly Mountain - Mt. Killaraus: Lifespring Font
28) Lascivious She-Devil - Zamahl Grotto: Den of Daemons (Magilou's Magnificent Menagerie Side Quest)
29) Unrepentant Recidivist Brute - Haria: Home of Old Beliefs (Hope Surpassing Reason Side Quest)
30) Chanting Shadow - Hexen Isle: An Island Wiped from Existence
31) Indomitable Dragon Swordsman - The Empyrean's Throne: A new Temple (Rangestsu Initiate Side Quest)
In order to get back to Hexen Isle, you must complete the side Quest "A Promise Made". Upon completion head to Stonebury and listen to the two exorcists. Travel to Hexen Isle will then be enabled.