Here is the full list of all 16 Howl of Iron achievements.
Complete Steelheart.
Activate Harman Fisher's invincibility shield. Find a way to EXECUTE your vengeance.
Kill Harman Fisher.
Execute an enemy that is panicking during combat.
Kill an enemy by throwing him another one.
Activate your howl 5 times during one playthrough.
A gift from the devs: UP UP DOWN DOWN LEFT RIGHT LEFT RIGHT B A
In Hunt mode, execute 3 Owlmen during one playthrough.
After the cutscene, kill the White Mutton before he calls more reinforcements.
Complete Steelheart without killing a single enemy.
Kill Harman Fisher without killing any of his reinforcements.
Oops! Fail the first jump in Steelheart.
Beat the whole game in less than 10 minutes.
Unlock all achievements in the game.
Execute 3 enemies in less than 3 seconds.
Find a way to kill the first Owlman.