Hiya.
I agree with Philippe Saner, except maybe for
Eternal Thirst. Yes, I wouldn't play it because of the "Whenever ..."-ability (not-possibility = 0 counters), but in casual it can be quite disturbing.
Some other suggestions and sorry if they were already mentioned in Philippe's link:
1) Sacrifice-mechanic -
Altar of Dementia,
Grave Pact and
Delraich /
Endrek Sahr, Master Breeder and creatures that offer advantages.
Grave Pact is a board cleaner for you.
2) UB-Control - Need I to say more? Yes, use
Gravestorm And beware, this can come (very) expensive regarding money and it will alter your deck quite strong because U-Control shifts to blue and for B-Control Vampires (
Gatekeeper of Malakir) are imho more suitable than zombies, but nonetheless: If you add in some disruption (and card draw) spells, you'll have a (very) good UB-Control-Zombie for casual.
3) W(U)B-Zombo-Cleric - Yes, very old regarding that this were one of the strongest tribal back in
Onslaught / Legions and today quite expensive BUT zombies and clerics (WB, sadly, so no blue) form a damn strong tribal which can even sandbag todays RG-Aggro-Decks without problems while they spit out tokens like hell and give you lifepoints beyond measure. If you're interested, I recommend you look for old clerics / zombies on magiccards.info and also demons
There is a broken mechanic where you can put out
Scion of Darkness in turn 2:
Dark Supplicant.
4) Splash red? Or UBR? There are a lot of possible choices, although I don't like decks that effectively play more than 2 colors because no / wrong mana = you're sitting ducks.
Cheers.