During the chapter bloodbath, there will be a body jason and nick will come across if both are alive. This will be the corpse of lady bradshaw. look above the corpse and there will be a stake jammed into the corpses heart. As jason, decide to stick to your rifle with you take the stake. This will give it to nick
Nearing the end in the chapter The Cocoon vault, if nick is still alive, he will go down the hole and place the dynamites. if he’s injured, pass the keep calm. there will be two keep calms if hes injured. Then after passing the keep calm, advance through the vault to plant more charges. you will need to pass three extra keeps calms. i recommend changing the difficulty to forgiving and to turn on single action qte in setting to make the keep calms easier. After you pass the keep calms, jason will activate the dynamites. nick will still be alive and the ancient warrior (bathulu or kurum it doesn’t matter which one it is) will corner nick. After passing a few qtes, nick will pull out the stake jason give him and attack the ancient warrior. pass the qtes and nick will kill them by stabbing them through the heart with the stake. you’ll unlock the achievement right after.