I was thinking about cards that I feel are underplayed in Modern and Pack Rat came to mind. That got me thinking about rats in general and reminded me of an old Standard deck I played in the Mirrodin/Kamigawa era that used Skull Collector in combination with Ravenous Rats/Chittering Rats plus Aether Vial to lock the opponent out. I brewed a mono black list and it was functioning better than I anticipated, but I wanted a little more versatility and removal. The printing of Wasteland Strangler got peaked my interest and I added white to the deck to provide more exile effects. This is what I've come up with:

Vial Rats/Death and Ratses/I Don't Give a Rat's Tax
CREATURES
3 Chittering Rats
4 Dark Confidant
2 Nezumi Shortfang
4 Pack Rat
3 Ravenous Rats
2 Skull Collector
1 Stonecloaker
4 Tidehollow Sculler
1 Typhoid Rats
2 Wasteland Strangler
SPELLS
4 Aether Vial
3 Inquisition of Kozilek
4 Path to Exile
2 Thoughtseize
LAND
1 Plains
3 Swamp
2 Godless Shrine
1 Isolated Chapel
4 Marsh Flats
4 Mutavault
1 Shambling Vent
2 Swarmyard
3 Urborg, Tomb of Yawgmoth

Sideboard Options
Celesital Purge
Deathmark
Disfigure
Duress
Hallowed Moonlight
Lifebane Zombie
Necroplasm
Oblivion Ring
Rest in Peace
Revoke Existence
Sin Collector
Surgical Extraction

In many ways, this deck is similar to some of the W/B Death and Taxes lists. This version opts to eschew cards like Thalia, Guardian of Thraben and Vryn Wingmare in favor of discard (the inclusion of both seems counter-intuitive to me, as the tax effects prevent your opponent from playing spells, so there really isn't a need to make them discard). The basic game plan is to rip apart your opponent's hand. You can then use Skull Collector + Chittering Rats + Aether Vial to deny your opponent from effectively ever drawing another card (empty opponent's hand, Vial in Rats during their draw step, pick Rat up on your turn with Skull Collector; if you catch your opponent drawing a non-instant, they're locked out). Pack Rat serves as your most resilient win condition and turns redundant discard spells into threats. Path to Exile and Tidehollow Sculler provide exile effects to turn on Wasteland Strangler, as does Stonecloaker, which can also pick up the Strangler for a replay. Swarmyard allows you to buy time against creature decks and has shown itself to be so potent that I've actually included a copy of Typhoid Rats in the main (Vialing in Typhoid Rats to block a fatty and regenerating it with Swarmyard feels so delightfully dirty). Mutavault is a generally powerful card that plays well with Aether Vial and adds to your rat count, growing Pack Rat. Urborg, Tomb of Yawgmoth allows you to play so many colorless producing lands and the drawback of being legendary is negated by being able to discard extras to Pack Rat. Dark Confidant keeps the cards flowing. Nezumi Shortfang is surprisingly good at flipping and provides a reasonable clock on a body that can be regenerated with Swarmyard.

The sideboard options mentioned are mostly general utility effects that provide additional means of exiling cards. Necroplasm is an under-appreciated gem that mops up tokens the turn you play it (but not Pack Rat tokens) and larger creatures the turns thereafter. You can bounce Necroplasm with Skull Collector or Stonecloaker as needed to avoid blowing up your own creatures.