"This ain't poison, but sure feels like it, right?"
Welcome to Y.A.A.D, short for Yet Another Allied Deck (which happens to sound a lot better that Y.A.A.L.G.L.D.D (Yet Another Allied Life Gain Life Drain Deck).
Built around passive damage via life drain, Y.A.A.D is a very simple BW Aliied deck, who's primary goal is to inflict as much suffering as korly/vampirily/humanly possible.
Been able to come back from near death (such as 1 or 2 life) to a full 20+, this deck's constant life gain effects can and will give us multiple chances to get back on our feet, all while imposing a "poison penalty" for our continuous existance.
Y.A.A.D In-Depth (or "Tools of the Slaughter)
Core Players:
Kalastria Healer, Zulaport Cutthroat and Drana's Emissary.All three will constantly inflict both life loss (on enemies) and gain (on us), so keeping these guys alive is of utmost importance, especially Kalastria Healer, since his ETB trigger can go off multiple times in the same turn with no drawback whatsoever.
Amplifier (or "The Guy You Need to Keep Alive"):
Cliffhaven Vampire.I cannot stress just how necessary this guy is. Seriously, dump all four of this guys in the field with a single Kalastria Healer and every new allied (tokens included!) will cost your enemy 5 life!
While his 4 toughness is more than enough to survive a Lightning Bolt, it's still a prime target for "anti-air" removal (or simply stronger removal, such as Grasp of Darkness). As such, it can benefit a lot from having a decoy on the field, keeping it safe for long enough.
Chance-Makers:
Lantern Scout, Ondu War Cleric, Vampire Envoy and, up to a point, Ayli, Eternal Pilgrim.
These guys will, more ofter than not, help you create opportunities to cause life loss on your enemies. Vampire Envoy, for exemple, can be equiped with Captain's Claws, so when it attacks it generates a kor ally token, which in turn triggers both Kalastria Healer's and Lantern Scout's ETB triggers, both triggering Cliffhaven Vampire multiple times in the same turn.
Token Factories:
Captain's Claws, Oath of Gideon and Gideon, Ally of Zendikar will all serve as token factories, churning allies every turn (sometimes even more than one a turn), giving you plenty of ETB triggers.
Decoys:
Drana, Liberator of Malakir,Gideon, Ally of Zendikar and tokens. Let's face it: we need decoys for all the removal earmarked for our lovely core cards. That's where these guys come in handy, demanding action before getting too big (Drana, Liberator of Malakir), ulting (Gideon, Ally of Zendikar) or going "full-rabbit" and swarming the field (tokens).
Removal & Control:
Anguished Unmaking and Declaration in Stone, the former serving as the most powerful directed removal at our disposal and the latter ensuring we don't get overrunned by small creatures or fall prey to a combo (much like our very combo).
Shoutout to Ayli, Eternal Pilgrim, who can become "The Exile Engine of Chaos and Food Fights" if left alone for too long (second skill gives us on-demand exile if conditions are met).