Vigil: The Ancient Guard Boss (No Damage / Hard)
The third boss in Vigil: The Longest Night completed on hard difficulty without taking damage. He's rather tanky and a bit RNG as to how readily he dives into the ground to reset to his initial phase (in this case only once but doing so multiple times isn't uncommon), so this fight can drag out. I forged Percival's Sword to +4 and added a bloodthirsty enchant to boost my damage (the bleeding effect is pretty effective and surprisingly works on skeletons and other undead).
The boss has a few different attacks to watch the cues for, but generally follows the pattern of "face becomes skeletal" before an attack with a green glow before an attack comes. He growls and takes a step when he's going to flip forward. His hands glow green and he slams his scythe into the ground when he is going to do his poison aura.
Because he doesn't really follow you it might be possible to kill him with throwing knives since the minions drop a ton of them (especially if you have all three pieces of Percival's armor for boosted item drop).
If you're wanting to play this game, it can be purchased here: https://store.steampowered.com/app/720560/Vigil_The_Longest_Night/
My Social Media Stuff:
https://discord.gg/bnv3V6t
https://twitter.com/CrankyTemplar