Here's my idea for a deadly boss battle. You enter a the throne room of the House of Kings, (Whether is be a Raid or Strike mission) the throne is empty, but there are two Kell Guards standing by the throne. While you're busy fighting them an Archon ambushes you, and kills one of your fireteam members. He is armed with a double Naginata with arc blades on both ends of the staff, can teleport in similar fashion to a Bladedancer, and can turn invisible for short amount of time. The way you combat him is this, after ambushing one of your teammates he will turn invisible and retreat then summon reinforcements allowing you to quickly pick up your teammate. As you fight his minions he will throw shock grenades, Arc damage Shurikens, and Razor's Edge from his hiding place(s), after you kill all his minions he will reveal himself as he charges you, at this point you can now attack him, with your guns, but be careful! You'll need a sword to parry his Naginata otherwise he will one hit kill you! While parrying him your teammates can damage him, after receiving a certain amount of damage, he will turn invisible and retreat then summon more reinforcement and repeat the process. After losing half his health, he will call in two Servitor Majors who will create invulnerable shields for him, you won't be able to damage him when he charges until you've killed both Servitors. For a quest line, killing him will reward you with his double Naginata as a Legendary Heavy weapon (Arc Damage).