Counterspell

Mistvault Bridge

Mistvault Bridge enters tapped.
Indestructible
{T}: Add {U} or {B}.

Seat of the Synod

Strange Augmentation

Enchant creature
Enchanted creature gets +1/+1.
Delirium — Enchanted creature gets an additional +2/+2 as long as there are four or more card types among cards in your graveyard.

Great Furnace

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Silverbluff Bridge

Silverbluff Bridge enters tapped.
Indestructible
{T}: Add {U} or {R}.

Unholy Heat

Unholy Heat deals 2 damage to target creature or planeswalker.
Delirium — Unholy Heat deals 6 damage instead if there are four or more card types among cards in your graveyard.

Thought Scour

Target player mills two cards.
Draw a card.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Death Rattle

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Destroy target nongreen creature. It can't be regenerated.

Thraben Foulbloods

Delirium — Thraben Foulbloods gets +1/+1 and has menace as long as there are four or more card types among cards in your graveyard. (A creature with menace can't be blocked except by two or more creatures.)

Cruel Witness

Flying
Whenever you cast a noncreature spell, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Dazzling Lights

Target creature gets -3/-0 until end of turn.
Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Gurmag Angler

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Vault of Whispers

Foul Watcher

Flying
When Foul Watcher enters, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Delirium — Foul Watcher gets +1/+0 as long as there are four or more card types among cards in your graveyard.

Chromatic Star

{1}, {T}, Sacrifice Chromatic Star: Add one mana of any color.
When Chromatic Star is put into a graveyard from the battlefield, draw a card.

Ephara's Dispersal

This spell costs {2} less to cast if it targets an attacking creature.
Return target creature to its owner's hand. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)