Deck Primer / Description

VALUE -- 19
Eternal Witness -- recursion
Skullclamp -- card draw, broken card
Yawgmoth, Thran Physician -- sac outlet + card draw
The Meathook Massacre -- board wipe + does damage
Ayara, First of Locthwain -- value
Gala Greeters -- value
Sedgemoor Witch -- value
Peregrin Took -- combos with experimental confectioner, generates some value on its own
Callous Bloodmage -- value
Evolutionary Leap -- sac outlet which helps you refill by saccing tokens or creatures which are about to die
Tireless Tracker -- value
Veinwitch Coven -- value
Night's Whisper -- card draw
Primal Vigor -- makes more tokens, kinda nice
Phyrexian Arena -- card draw
Sylvan Library -- card draw
Trudge Garden -- value
Corrupted Conviction -- card draw
Village Rites -- card draw

COMBO -- 6
Blood Artist -- combos with sac outlet
Zulaport Cutthroat -- combos with sac outlet
Ashnod's Altar -- combos with Valentin and Grave Pact/Dictate to clear all enemy creatures; is generally a good card
Bastion of Remembrance -- combos with sac outlet
Spike Feeder -- combos with lisette + devoted druid/crystalline crawler for infinite life. There are other combos too. Most important card in the deck bc of its interactions with Lisette
Experimental Confectioner -- combos with peregrin took

UTILITY -- 17
Dictate of Erebos -- recurring removal
Grave Pact -- recurring removal
Reclamation Sage -- targeted removal on a creature
Acidic Slime -- targeted removal on a creature
Beast Within -- instant speed spot removal
Haywire Mite -- instant speed spot removal on a creature
Tear Asunder -- flexible removal
Bone Shards -- spot removal
Regrowth -- flexible recursion
Mortality Spear -- spot removal
Animate Dead -- flexible recursion
Heroic Intervention -- good protection spell
Infernal Grasp -- flexible removal
Deadly Brew -- flexible recursion + sometimes useful removal
Toxic Deluge -- great board wipe
Phyrexian Reclamation -- flexible recursion
Veil of Summer -- good protection spell AND it beats counterspells which is great

RAMP -- 16
Cryptolith Rite
Paradise Mantle
Springleaf Drum
Sol Ring
Farseek
Rampant Growth
Three Visits
Nature's Lore
Devoted Druid
Cultivate
Kodama's Reach
Sakura-Tribe Elder
Wood Elves
Solemn Simulacrum
Wild Growth
Utopia Sprawl
Crystalline Crawler

LANDS
Mirrex
High Market
Nurturing Peatland
Llanowar Wastes
Woodland Cemetery
Undergrowth Stadium
Deathcap Glade
Command Tower
Temple of the False God
Darkbore Pathway
Temple of Malady
16 Forest
13 Swamp

UPGRADES

$$
Overgrown Tomb -- pretty good land upgrade and helps you find black with nature's lore and three visits
Parallel Lives -- expensive value card which doesn't benefit you massively (it's great with more reliable token generators but your combos don't require it)
Phyrexian Tower -- sac outlet
Yavimaya, Cradle of Growth -- good for mana fixing
Urborg, Tomb of Yawgmoth -- good for mana fixing
Boseiju, Who Endures -- powerful utility land
Takenuma, Abandoned Mire -- powerful utility land
Ancient Tomb -- broken land
Mana Crypt -- broken ramp
Damnation -- good board wipe
Reanimate -- good recursive spell very strong utility
The One Ring -- good value card
Black Market Connections -- good value card
Deadly Rollick -- good spot removal
Assassin's Trophy -- good spot removal

Tutors
Worldly Tutor
Demonic Tutor
Vampiric Tutor
Diabolic Intent
Wishclaw Talisman
Invasion of Ikoria
Finale of Devastation
Green Sun's Zenith
Chord of Calling
Dryad Arbor (to find with Invasion, Finale, Green Sun's Zenith, Chord of Calling)

1 mana ramp creatures:
Fyndhorn Elves
Llanowar Elves
Elvish Mystic
Elves of Deep Shadow
Birds of Paradise
Deathrite Shaman (requires fetches)

these cards accelerate you way faster but are less resilient -- you might start by replacing cultivate or kodama's reach but it'd suck if you don't spend that mana on strong enough value and then they get board wiped later

other common cards you may want to consider in G/B:
Scavenging Ooze -- graveyard hate
Opposition Agent -- search hate
Dauthi Voidwalker -- similar effect to Valentin
Harmonize -- card draw
Read the Bones -- card draw
Sign in Blood -- strictly worse night's whisper