Essentially, this deck utilizes Ogre Slumlord as a main win condition.
Since Ogre Slumlord's ability enables you to put a 1/1 rat creature token into play every time a creature dies on the field, the Pack Rat cards get major buffs.
Plus, adding as many Parallel Lives into play as you can just creates more rat tokens, buffing your Pack Rats to very high numbers.
Did I mention that Ogre Slumlord makes all rats gain Deathtouch?
Make sure to stick those Alpha Authorities onto your Slumlords and Pack Rats to keep the pesky removal spells out of the way.
Vampire Nighthawks and Gifts of Orzhovas will keep your enemies flyers in check.
I personally love Curse of Death's Hold. It completely shuts down a lot of weenie/aggro decks. Yes, it costs 5 mana in total to play, but it's just awesome. It also takes care of those 1/1 unblockables (eg; Tormented Soul and Invisible Stalker)
I chose Liliana of the Dark Realms over Liliana of the Veil because of her +1 ability: mana fixing. It's nice to have at least 6 mana on the field to make this deck really competitive, and when you get at least that much- Liliana's +1 ability can just act as pulling a land to discard for another Pack Rat. Her -3 and -6 abilities are quite useful too if needed and can sometimes be a win condition, especially when paired with Rancor!
I put some Pit Fights and Prey Upons into the sideboard to act as even more removal to make way for your rat army to get in for damage- since all your rats will have deathtouch, you can fight them against your opponents creatures to get rid of them AND gain a rat token (or two depending on if you fight a creature or token) due to Ogre Slumlord's ability... which will buff your Pack Rats again.
Predator's Rapport for some life gain. Best used late game when you have a bunch of huge rats out. Add their power and toughness together and gain that much life. If played at a good time, this card is a life saver.
Last but not least, Wildwood Rebirth, just in case your opponent is playing tons of removal.
