Looks good! These might interest you: Pitiless Plunderer, Black Market, Ilysian Caryatid, Skullclamp, Grim Haruspex, Fruit of the First Tree, Supernatural Stamina, Undying Evil, Kaya's Ghostform, Cauldron of Souls, Mimic Vat, Nim Deathmantle, Death's Presence, Mazirek, Kraul Death Priest, Morality Shift, Memorial to Folly (can loop with World Shaper)

you should add Necrologia. if Underrealm Lich is on the field and you pay around 20 life you'll draw your whole deck, makes creatures that get bigger from cards being in the graveyard huge.

you can do a lot with Underrealm Lich

Deadly Rollick is a new removal spell that can cost 0 when you have your commander out. also Eat to Extinction is another removal that has built-in self-mill on it, that can deal with planeswalkers too.

there are other removal on a creature, like Merciless Executioner, Fleshbag Marauder or Shriekmaw.. and a new one from zendikar rising, Demon's Disciple.

Mindwrack Harpy makes lord of extinction bigger quicker.

try Deadbridge Chant

these are some of the spells that come to mind when filling the graveyard. you may want to consider these. Drown in Filth Commune with the Gods Gather the Pack

Lotleth Giant Doomgape good targets for jarad

Gemrazer and Keeper of the Dead are also good removal on a creature, but the latter might be hard to find since it's an old card. Doomed Necromancer can be a sacrifice outlet on a creature with recursion, or you can go with the Altar of Dementia edh staple.

how about Gamekeeper and Skull Prophet?

you have very few card draws in your deck for my liking i suggest Ohran Viper Disciple of Bolas Elder Gargaroth Ripjaw Raptor and Treeshaker Chimera as card draw on creatures. i love your addition of Clackbridge Troll as conditional card draw on a creature that can be used as fodder for jarad too.

Ghoultree can be turn 3 or 4, 1 mana 10/10 at the right circumstance, and can deal a lot of damage early on.

Hydra Omnivore is also good, when recurred early and attack one opponent w/o blockers to deal damage to every opponent too.

Fiend Artisan is a new card that fits well into your deck, as well as Necrotic Wound. also, unless you have a budget or you don't want to be a target in your playgroup, you can add Sheoldred, Whispering One. it will be so effective, but it might draw the ire of your playgroup.

Modal Double faced cards are great for edh decks now. Bala Ged Recovery  ^Flip or Agadeem's Awakening  ^Flip are great for the deck.

Tangled Florahedron  ^Flip imo is better than Krosan Restorer or Leyline Prowler. Hagra Mauling  ^Flip can be good, but it depends on the playgroup. Usually, players doesn't have basic lands, especially competitive players.

One more thing! Nissa of Shadowed Boughs is a new golgari planeswalker, you might want to consider, that can recur a creature on the turn you pay her for 4 mana, as long as you have a land in your hand.

wow! thanks guys for all the suggestions! I have been so busy, and haven't update much of this deck since early this year.. I will update this deck this weekend, with all the good suggestions you have given..

@king-saproling - thanks for the suggestions! I will consider those..

@casual_competitive - I'm not much of a 2 card auto win combo kind of player, especially since i already have Jarad, Golgari Lich Lord + Phyrexian Devourer in the deck.. but thanks for the suggestion!

@VEILofAUTUMN - thanks! I might add one of them, it depends on playtesting, since either of them are creatures.. maybe Deadly Rollick..

@vileplume23 - hmm.. these are good on indestructible creatures, but i can't target threats like Ravenous Chupacabra.. i'll consider those.. thanks!

@backdoorbonus - that's a cool new card! affect other players too.. i might add that! thanks for the suggestion!

@cakes25 - it's an instant graveyard fill, but it might be too slow and too random of a card recursion.. but thanks!

@TRANSFORMERS159 - thanks for the suggestions.. however, i have considered those before and it's just to slow for me since those are sorceries compared to Grapple with the Past & Grisly Salvage..

@Cloud777 - Lotleth Giant only affects one opponent, and it's hard to cast or cost higher life to Reanimate, but i might consider Doomgape.. it can be lifegain on a stick.. thanks!

@masayoshishido - Doomed Necromancer can be a cheap creature recursion, Keeper of the Dead will depend on the consistency of creatures on my graveyard, Gemrazer is good on certain situations bu can be vulnerable to single target removals that can kill gemrazer and the mutated creature, Altar of Dementia might be reconsidered.. thanks for all the suggestions!

@antlers12 - Gamekeeper might be a dud, since it needs to die then it needs to have enough noncreature cards to fill a bit of the graveyard and i don't have a lot of sac outlets.. also, creatures in the graveyard is needed for the gameplan of the deck, it might be counterintuitive to mill noncreature cards with Gamekeeper.. but Skull Prophet is a definite inclusion! thanks!

@sigiledwatch - ohh.. true, however putting things in my graveyard can be card draw in a way that's why i don't put a lot of card draws.. but i get what you mean, i might consider some of those cards.. thanks!

@mylene800 - i have considered Ghoultree before, though i'm not sure how it would be good.. i would playtest it again with the changes i would make, and check if it's worth as an inclusion.. however, Hydra Omnivore might be meh in the deck.. 6 mana, 8/8 creature that needs to connect for the best results might be hard in turns 4-6 earliest.. not having trample is not good.. but thanks for the suggestions!

@megantrongriffin13 - both Fiend Artisan and Necrotic Wound are great new changes in the deck! I'll check about Sheoldred, Whispering One.. It might not be a salty preator card, on my playgroup.. thanks!

@lola82600 - yeah! i was excited on adding some of those to my edh decks as well! I will definitely include Bala Ged Recovery  ^Flip and Tangled Florahedron  ^Flip! not sure about Agadeem's Awakening  ^Flip, depends on playtesting if the price of the card versus being useful game ender or just a land most of the time.. I'll consider Nissa of Shadowed Boughs too! Thanks for the suggestions!

try these new cards from streets of new capenna

Cemetery Tampering Shakedown Heavy Topiary Stomper

Atrocious Experiment can be another Funeral Rites if you need more card draw while adding more self milling effects

Druidic Ritual is another self mill card and can recur a land and a creature when you need it during later turns

another new card is Monster Manual that has self milling effect but can summon a creature from your hand cheap

Ambitious Dragonborn and Ancient Brass Dragon are good new creatures that can grow big in the deck

Circle of the Land Druid and Gray Slaad might interest you

@vehiclemaster - Cemetery Tampering looks slow, after casting this, it doesn't affect anything yet.. might playtest it first.. Shakedown Heavy has a lot of hoops to go through just draw a card.. and Topiary Stomper is a one time ramp only, and doesn't affect the board if i draw it very early.. The dispensable creatures i have for ramp feels better.. thanks for the suggestions though..

@RoxieRoxie - Ambitious Dragonborn is lacking compared to other big creatures i have already included in the deck.. like Carrion Grub, Old Stickfingers and Wall of Blood are much better.. Ancient Brass Dragon looks like a fun card though.. might be a card that overturn the situation of the game.. might consider it, but not soon.. since it's still costs high as of the moment.. thanks for the suggestions!

@Tiyos99 - thanks for the suggestions.. although Circle of the Land Druid is an okay disposable land recursion and self milling cheap creature, other options already included in the deck is much better w/o waiting for it to die.. Gray Slaad is not good.. aside from the adventure side of it, the payoff of having 4 or more creatures in the graveyard is underwhelming..

@ZXddgsw12 - Thanks for the suggestions! Atrocious Experiment and Druidic Ritual might have a place in the deck.. i'll have to see if i can replace some of the cards.. Monster Manual might be too slow though..

i suggest either Sadistic Sacrament or Praetor's Grasp to protect your graveyard

Try these new cards, might interest you.

The Cruelty of Gix

Urborg Repossession

Writhing Necromass

Deathbloom Ritualist and Skyfisher Spider are new cards you might want to consider