Here is the full list of all 25 Boundless Paths achievements.
Conquer 1 Map
Conquer 5 Maps
Conquer 10 Forts
Cast 40 Spells in 1 Run
Reach Day 38
Destroy 6 Lairs by Day 15
Conquer 50 Forts
Achieve Victory by Day 28
Reach Day 43
Hoard 5000 Gold
Electrocute for at least 70HP 30 times
Cast 11 Spells in 1 Night
Conquer 3 Forts in 1 Night
Destroy 4 Lairs in 1 Night
Apply Cruel Finisher to monsters with 3+ Debuffs 2000 times
Cannon AOE 5 Stunned & Slowed targets 100 times
Trigger a 100HP Curse Explosion with another 25 times
Conquer 5 Forts in 1 Night
Reach Day 21 without any monsters reaching the base
Conquer 1 Large Map
Conquer 5 Large Maps
Reach Day 49 on a Large Map
Conquer a Large Map by Day 39
Conquer 3 Large Forts in 1 Night
Destroy 6 Lairs in 1 Night (Large Map)