Here is the full list of all 15 Halftime Heroes achievements.
Add one mode to a new game
Add four modes to a new game
Reach level 10 in any spell
Get any stat to 10
Kill your first boss
Get a score of 18 or higher when throwing the dices
Reach 10 strength
Reach 10 agility
Reach 10 wisdom
Reach 10 intelligence
Reach 10 luck
Reach 10 willpower
Kill 1000 monsters in one playthrough
Kill 3000 monsters in one playthrough
Kill 5000 monsters in one playthrough