This deck pretty much has one theme, discard with a graveyard sub-theme. Blue is a great add, there is plenty of blue-black discard oriented cards available and as you pointed out has counterspells. Unfortunately you have a lot of things in the deck that conflict with this construction.
Cephalid Retainer - Obviously your trying to combo it with Royal Assasin, and get through for flying damage... clunky, and unnecessary with a working Nyxathid or Avatar of Woe.
Ogre Marauder - I like this card, but it's definitely geared towards aggro, while the rest of the deck is not.
Bad Moon - The only other purely aggro card in the deck, best in a Weenie deck with plenty of small black attacking creatures. Not a card I expect to see with Guilt Feeder, Sangromancer, Avatar of Woe, Mortivore, etc.
Arcanis the Omnipotent - Card draw is great... this guy not so much. Really you could do much better with spells like Flux, or Memory Jar that powers up your own Mortivores.
Second Sight - Is a TERRIBLE card. It's only ok in mill, and even then it's so costly that it still sucks
Retraced image - you said it yourself, you only have mostly 1 of cards, this is would be a good add if you had 4 of everything. It's not good in this deck.
Ancestral Recall - You have 2? Awesome! But even though I play casual, I still obey vintage rules. Somebody out there has a deck with 4 black lotuses, 4 ancestral recalls and 4 time walks... I don't want to see that deck, where would the fun/challenge in it be, for the both of us? I'd suggest limiting myself to 1.
Nyxathid - I'd keep this card but I'd consider adding cards like Persecute or Hand of Tourach to support it. Maybe a spector or two.
I'd suggest looking at cards like
Persecute
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=83199
Hymn to Tourach
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=159180
Spectors
http://gatherer.wizards.com/Pages/Search/Default.aspx?action=advanced&type=+[%22Creature%22]&name=+[Specter]
Breathstealer's Crypt
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=3734
Consult the Necrosages
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=87923
Flux
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=4485
Magus of the Jar
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=126287
Recoil
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=23154
Wistful Thinking
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=124055
Memory Jar
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=8841
Anyway welcome back to magic, hope this gives you some ideas.