Full list of all 10 King's Guard TD achievements worth 1,000 gamerscore. It takes around 8-10 hours to unlock all of the achievements on Xbox One.
Defeat the Lord of Dragons
1,000 Dragons killed
1,000 Mages killed
Complete Dark Revenge Campaign
12,000 Enemies killed
2,000 Warriors killed
8,000 Enemies killed
Complete Call of Dragnor Campaign
4,000 Enemies killed
Build 3 Arrow Towers