Here is the full list of all 48 Battle Chasers: Nightwar achievements worth 1,000 gamerscore.
Complete a dungeon on Legendary difficulty
Kill 500 enemies
Kill one of the Beastmaster's Targets
Bring Alumon into the party
Complete The Dig
Unlock a Level 3 Battle Burst
Complete Junktown
Find Monika
Find Knolan
Complete the Path of Fangs
Craft an item with less than 10% success chance
Unlock a Beast Perk
Complete the Iron Outpost
Recover an item from the Mystery Cube
Craft an item
Make it to the road
Complete Deadwatch
Complete Strongmont
Complete the Crimson Garden
Complete the Mana Rifts
Kill C'drall
Complete all dungeons on Legendary difficulty
Start NG+
Finish the game on NG+
Craft 50 items
Craft 10 Rare Items
Craft 10 Epic Items
Craft a legendary item
Reach level 30
Complete 50% of the Bestiary
Complete 100% of the Bestiary
Defeat the Pirate Captain
Catch 50 Fish
Catch an Epic Fish
Complete the Fishiary (100% catch all fish)
Unlock 50% of the Lore Book
Unlock 100% of the Lore Book
Acquire 1 of the Heroes' Ultimate Weapons
Acquire all of the Heroes' Ultimate Weapons
Unlock a Hero Skin
Unlock all Hero Skins
Unlock All Battle Bursts
Get a Mid level score at the Battle Arena
Get Max Score in the Battle Arena
Acquire 100,000 gold (culmulative)
Acquire 200 Shadow Coins
Get all three chests in The Winding
Kill all the Beastmaster's Targets