Hades, Sorcerer of Eld

Vigilance
Echo of the Lost — During your turn, you may play cards from your graveyard.
If a card or token would be put into your graveyard from anywhere, exile it instead.

Emet-Selch, Unsundered

Vigilance
Whenever Emet-Selch enters or attacks, draw a card, then discard a card.
At the beginning of your upkeep, if there are fourteen or more cards in your graveyard, you may transform Emet-Selch.

Emet-Selch, Unsundered // Hades, Sorcerer of Eld

Emet-Selch of the Third Seat

Spells you cast from your graveyard cost {2} less to cast.
Whenever one or more opponents lose life, you may cast target instant or sorcery card from your graveyard. If that spell would be put into your graveyard, exile it instead. Do this only once each turn.

Lier, Disciple of the Drowned

Spells can't be countered.
Each instant and sorcery card in your graveyard has flashback. The flashback cost is equal to that card's mana cost.

Spellweaver Volute

Enchant instant card in a graveyard
Whenever you cast a sorcery spell, copy the enchanted instant card. You may cast the copy without paying its mana cost. If you do, exile the enchanted card and attach this Aura to another instant card in a graveyard.

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Mystical Teachings

Search your library for an instant card or a card with flash, reveal it, put it into your hand, then shuffle.
Flashback {5}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Inundated Archive

This land enters tapped.
{T}: Add {U} or {B}.

Waterlogged Teachings

Search your library for an instant card or a card with flash, reveal it, put it into your hand, then shuffle.

Waterlogged Teachings // Inundated Archive

Thunderclap Drake

Flying
Instant and sorcery spells you cast cost {1} less to cast.
{2}{U}, Sacrifice this creature: When you next cast an instant or sorcery spell this turn, copy it for each time you've cast your commander from the command zone this game. You may choose new targets for the copies.