Excellent read Noloetazier
At first i thought Niellefersne's killer was Corguevais coming back to make sure the truth was not discovered ...but as you pointed out is a Hyur not an Elezen...Then i thought it was an assassin hired to stop the necromancy from happening because its forbidden....But now i'll place my bets that the hooded guy was actually Warburton , that would explain why he didn't do anything to Ascillia and why Niellefresne was so shocked ..because the crypt was empty! remember through an Echo we find Corguevais and Ascillia alone with Warburton right at the moment he supposedly dies? what if they used something to make him appear to be dead but was just temporal?

Now onto Jinrya Geky's find lol nice catch .. if you are right then it was Fenrir who had fun feasting on Garleands ..but who summoned him?