Igheris seems a bit out of flavour it shouldn't have flash or first strike since they are inherently white (flash part white mostly blue) and white is the enemy colour of both black and red plus its sacrifice ability should have a fixed number e.g sacrifice 5 non-demon creatures you control as all non demons could be anywhere between 1 and infinity and demons seldom sacrifice permanents its generally just creatures so currently basically it kills mountains at the cost of all lands, enchantments artifacts planeswalkers and creatures that dont have the demon card type.
Krell, Phyrk and Cruor-Lobov seem like legitimate cards that could see print if ever they were considered as they have flavour for the type of creature their trying to be and their colours
however Fateweave Chronicler seems a bit confused on what it wants to be it is a revive engine a shroud card drawer and a potentially overpowered graveyard feeder. Overall a card that has its hands in every blue-black archetype possible. it is inherently overpowered and while igheris only needed minor tweaks for flavours sake this spits on the proverbial cake that is magic flavour at its heart. what you need to do is take a step back see what this card truly needs to be flavourful as a chronicler eg card drawing/ scrying and then try and take out all the extra jumble that you have tried to cram into one card it could be a great card it just seems as if you have got two on their own strong individual cards and gone "I know how to make this good cram them both onto one card with a massive text wall and make an intensely overpowered blue-black monstrosity" I mean I'm a big blue-black player but that is just unfair especially for only 5 mana.
I love Phyrk the most of these cards as alongside his intense flavour especially the lingering poison effect he gives to creatures that truly mimics a spreading poison he could also potentially spawn some new card ideas maybe make his bow as an equipment or some other venomous/ plague baring zombies to spice up the forum.