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