Recycle that graveyard. A few creatures that grow with every death, and little creatures with ETB effects. A war of attrition for my opponents.

Golgari : Black and Green

Whenever another creature you control dies, you get an experience counter.

At the beginning of your end step, choose target creature card in your graveyard. If that card's mana value is less than or equal to the number of experience counters you have, return it to the battlefield. Otherwise, put it into your hand.

Commander
Meren of Clan Nel Toth

Artifacts
Bow of Nylea
Bubbling Cauldron
Crucible of Worlds
Palantir of Orthanc

Creatures
Acolyte of Affliction
Aggressive Mammoth
Arborback Stomper
Author of Shadows
Beledros Witherbloom
Big Game Hunter
Blood Artist
Bogbrew Witch
Braids, Arisen Nightmare
Butcher of Malakir
Carrion Feeder
Creakwood Liege
Deathrite Shaman
Eternal Witness
Festering Newt
Giant Adephage
Gixian Infiltrator
Grim Flayer
Highland Game
Jugan, the Rising Star
Kraul Whipcracker
Lumberknot
Mazirek, Kraul Death Priest
Morbid Opportunist
Phyrexian Broodlings
Ramunap Excavator
Ravenous Chupacabra
Rot Shambler
Sangromancer
Sheoldred, Whispering One
Spore Frog
Vein Ripper
Willow Geist

Enchantments
Agent of the Iron Throne
Binding the Old Gods
Deadbridge Chant
Deathreap Ritual
Dictate of Erebos
Fight Rigging
Golgari Germination
Moldervine Reclamation
Raised by Giants
Rune of Mortality
Trespasser's Curse
Vampiric Rites
Virtue of Persistence

Instants
Bake Into a Pie
Bleed Dry
Feed the Serpent
Grisly Salvage
Putrefy
Return to Nature

Planeswalkers
Vraska, Golgari Queen

Sorcery
Casualties of War
Diabolic Tutor
Relentless Pursuit
Remorseless Punishment
Scale the Heights
Witherbloom Command

Lands
Bojuka Bog
Darkmoss Bridge
Forest x 10
Foul Orchard
Gingerbread Cabin
Golgari Guildgate
Golgari Rot Farm
Grim Backwoods
Hissing Quagmire
Jungle Hollow
Leechridden Swamp
Myriad Landscape
Necroblossom Snarl
Swamp x 11
Temple of Malady
Witherbloom Campus
Woodland Chasm