1. Sakura-Tribe Elder great mana fixer and has sacrifice theme.
2. Deathrite Shaman many uses and synergy with jarad.

it seems like deathrite has negative synergy with jarad by pulling creatures out of the graveyard

Bayou , Misty Rainforest because lands.

Overgrown Tomb For something to fetch and Jarad's Orders because it gets things into your graveyard

Savra, Queen of the Golgari is Jarad's sister and perfect compliment card. And you can't go wrong with Wreath of Geists to capitalize on dead stuff.

Buried Alive and Entomb for more placing in graveyard. Hopefully someone else recommends some reanimation stuff, currently there is a lot of stuff going to the yard and not a lot going back out.

Endless Ranks of the Dead and Gravespawn Sovereign would be my picks. let's get a little more tribal going on. I want to put this here before there are too many non-zombie creatures. Use the tokens to block AND pull from the graveyard. Tribal zombies was one of my first decks, so I'd love to see some more tribal cards come into the fold.

Demonic Tutor and Vampiric Tutor to find the cards in the deck that you want (also Imperial Seal but i am out of suggestions)

it also needs a better manabase

Nighthowler because pseudo jarad, and Tarmogoyf because lhurgoyf

Strength from the Fallen because it is crazy in any dredge deck that can play enchantments, and Nyx Weaver so you can grab anything important if you need to.

Creature count is kinda low so far for a dredge deck. So in keeping with the Zombie theme let's add:

Returned Centaur Vulturous Zombie

1. Lotleth Troll good synergy for Jarad and Dredge
2. Brawn gives all your guys trample for being in the graveyard, which is where we want him.

Phytotitan for recurrable 7/2 with Gerard and Greater Good for draw with Phytotitan

Wound Reflection and Phyrexian Processor

Suggestion 1: Damnation - every EDH deck needs a reset switch and what better than the mono-black wrath?

Suggestion 2: Sword of Feast and Famine . I love the Swords, they are wonderful cards. At first I was trying to decide between Sword of Body and Mind or Sword of Light and Shadow but couldn't decide whether the deck is trying to self mill, or with cards like Nighthowler and Wreath of Geists benefit from board wide graveyard growth. So I settled on the flavorful Golgari sword, and anyway, who doesn't love untapping all their lands mid turn??

1 Triskelion

2 Tooth and Nail

Golgari Grave-Troll and Dakmor Salvage . They're both really easy Dredge sources.

Sheoldred, Whispering One

Kokusho, the Evening Star (legal now)

Sorry didn't give reason. Sac Kokusho with Jarad, RTB next upkeep thanks to Sheoldred, lather rinse repeat.

Reanimate and Animate Dead because bringing things back from the dead is always a plus

Grisly Salvage and Nighthowler for sure!

Salvage for the filling of your graveyard, Howler to benefit from it.

Awakening Zone because why not have mana that can also be sac fodder or thrown under a bus without trample? Grave Pact because sharing is caring. You should let everyone else have a chance to sac. I would also suggest the dictate of erebos and butcher of malakir for the same reasons, but the first 2 are my 2 cards and hopefully someone picks up on what I left.

Bonehoard to feed off of having a huge graveyard and is great for Jarad's fling effect.

Putrefy great spot removal at instant speed.