Here is the full list of all 24 Dungeons & Dragons: Chronicles of Mystara achievements.
Kill 300 Enemies of Any Type
Complete Tower of Doom
Complete Shadow over Mystara
Reach Overall Player Level 10
Complete all 3 Tiers of the Challenge “Help Wanted.”
Complete all 3 Tiers of the Challenge "Curb Stomp-A-Thon."
Complete 1 Challenge Tier of “Slick Hammers”
Reach Overall Player Level 5
Complete 1 Challenge Tier of “Pointy Things and Slings.”
Complete 1 Challenge Tier of “Fry ‘Em Up.”
Kill 30 Enemies of Any Type
Kill 1000 Enemies of Any Type
Complete all Tier 1 Challenges
Complete all Tier 2 Challenges
Complete all Challenges
Gather all Treasures
Gather 10,000 Gold (SP)
Reach Overall Player Level 20
Complete 1 Challenge Tier of “Paralyzation Nation.”
Complete all 3 Tiers of the Challenge "Till Death Do Us Part"
Complete all 3 Tiers of the Challenge "Petting Zoo."
Complete all 3 Tiers of the Challenge "So Desperate!"
Complete all 3 Tiers of the Challenge "Loot Master."
Complete all 3 Tiers of the Challenge “Spellcaster.”