Let's me give you a big hint at the problem I faced in my last matchups:
If you said: missing a color, then line up for your prize! (Note, I have no prizes.) I hate being right, although I don't get tired of it.
On the other hand, it confirms that this deck needs a little bit more. Being efficient may not be enough. These games were played before Phyrexian Boon had been removed so I still have a little room to play with but these games just made me groan inside. Both were multiplayer games, so I had time to develop my board but it didn't matter; I could not get the key third color and that led to everything collapsing. I was denied access to some of my most powerful spells, the Charms, because of it.
Reviewing the decklist, I'm wondering if the concerns that led me to add Phyrexian Boon, namely the necessity of removal + attempt to shorten the game clock, were unfounded. I have 10 removal spells without Boon. Maybe what I really need is an additional Mountain and some card draw. Curiosity is fun but something that isn't reliant on another permanent is probably wise. Also, if I could put in something that got a bonus from either the Liege (blue/black creature) or the Familiar (blue/red spell) that might be ideal.
Desperate Ravings might be the solution I'm looking for. Between the colors being spot on and the card draw, that could help Kickback smooth out some issues. I wish there was a hybrid mana card to add in and so a review of Ravnica, Return to Ravnica, Shards of Alara and Shadowmoor blocks may be in order. Hybrid mana is a godsend to decks in this position so I may as well take advantage of it, if it's available.