What this deck needs is infinity more tutors and draw. You need much faster/more consistent ways to go off, since you've picked a pretty piss poor combo to field in multiplayer. 3 cards and it only hit one player, that isn't the best way to try and win games. Luckily, Black and Blue have some pretty good **** for that. I'm really leaning towards something like Dimir House Guard since it can transmute for either 4 mana spell. Diabolic Tutor is fine... but it's kinda slow. Your ideal cards are things like Vampiric Tutor, Enlightened tutor and Demonic Tutor, but they also hurt the wallet. Idyllic tutor isn't bad, but only grabbing Puca kinda sucks : /.
Eh, let's try this again actually. Thinking about it more, I would build the deck somewhat differently. Leyline of the Void is the nuts since it locks everyone at a 0 card graveyard, which makes your life much easier when it comes to killing them off. Leyline also opens up a lot of possibilities for this deck. I always pair it with Helm of Obedience since it give me a cool way to exile a player's library for a single mana. It's nice to have alternative ways of winning every now and then. It also lets you field Web of Inertia, which is just a solid form of defense. There's no need for mass removal and fogs when creatures can't attack you. Now, I get that you won't always start with a Leyline, but that's where a Relic of Progenitus or two come in handy. Just crack one after you establish a Leyline to clear the graveyards and replace the Relic. The cantrip effect is just gravy ^_^. Now, as you may have noticed, Leyline is another 4 mana spell. That makes the DHG that I previously mentioned much more enticing. It's still no Demonic Tutor, but now it transmutes for every single combo piece. Not bad eh?
From there you just cut White and add more good Black and Blue cards. Rhystic Study is great. Mystic Remora is great. Syphon Mind is ok, but our 4 drop slot is already clogged. I'd probably avoid adding more. Lim-Dul's Vault is solid, you can't go wrong with that. Phyrexian Arena would probably work here actually. A U/B deck should have an easy time paying 1BB by turn 3.
I'm not a fan of Ponder is decks that can't shuffle their library with fetchlands. If you see 1 good and 2 dead cards then you're just a sad panda. I'd happily run Preordain before I ran Ponder since it can naturally hide bad cards, even though it doesn't dig quite as far. It's still a better card to use if you don't have fetches.
I never run more than 1 Helm either. It's almost never your primary win condition and forking out $20.00 for a set of cards that can only be used with Leyline of the Void isn't ideal. It's also stone dead if your Leyline dies, and drawing more than 1 is pretty much useless.
Looking much more solid. Way better draw, strong tutors, impenetrable defense, good early game filtering, etc. The only questionable cards are Lapse and Negate. Negate I can understand since it's a spell that actually does something, but I still wouldn't ever play it. Lapse, on the other hand, doesn't do anything. Like, I'm a big Limited guy, and I understand how broken cards like Memory Lapse and Grasp of Phantoms when you're playing an aggressive W/U deck and you're ahead on the board. It's a Timewalk that's going to win you the game more often than not. Still, this isn't a duel. Timewalking one opponent doesn't really do much in multiplayer. Yeah, you pissed him off, but that tempo swing is just so minor when he's the only one who was set back. I really feel like the card just plain does nothing. Tempo plays aren't very strong in multiplayer, that's all there is to it.
Now, I hate counters. Loathe them. I hate any 1-for-1 in multiplayer for that matter. I'd rather go all-in on my deck and just hope to push past hate by fielding a strong, resilient deck that can handle a good deal of what will be thrown at it. Still, if you HAD to play counters (and again, I am not endorsing them at all) I would play with Arcane Denial or something. I do not give a flying **** about letting someone draw a few extra cards if it means that my counter cantrips. Like, could not care less. It can also be used to "filter" dead draws like extra Webs if needed, so it's never just going to sit there and be useless. But yeah, the card basically reads "counter a spell and a draw a card" for 2 mana in my mind. The card disadvantage is virtually meaningless (for the same reason that tempo plays are virtually meaningless).
I wouldn't want protection against burn, I'd use it to my advantage. If someone was trying to burn everyone down, then I'd put Exsanguinate in my deck to not only gain me more life than a Red player could ever hope to burn out, but I'd also build on the damage being done to people to hopefully kill them off. I mean, Witchbane Orb is... a card... but I wouldn't ever "hate" on burn with counters when I could just field an amazing card like Exsanguinate that basically shuts down all burn strategies.
As far as removal goes, I really don't know what your plan is. You realize that, at this point, you're talking about 3 card combos that require protection and only beat single opponents right? Like, I hope you can appreciate how flimsy of a gameplan that is. Here's the reality of the situation; you're going to pull this **** off once. Once you "go off" and kill a player, the jig is up. Suddenly everything will become clear and people will do everything in their power to stop you. That's the biggest weakness of your deck. It's never "too late" to stop you. You need a lot of cards and a lot of setup time to kill. You are not going to stop the dedicated hate of multiple opponents by 1-for-1ing them with counters (conditional counters at that). If I were playing this deck, those cards would be tutors, draw, or recursion (Yawgmoth's Will for example). I would just do everything in my power to combo out as fast + as much as I possibly could. Protection is only useful if you're facing hate and if you can adequately defend against it. Those are 2 very big "ifs" in my mind. I don't try and chase wins that I'm realistically never going to get, I'd rather just make my deck as consistent as possible and hope for the best.