Gurmag Angler

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

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Shambling Attendants

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Brainspoil

Destroy target creature that isn't enchanted. It can't be regenerated.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Careful Study

Island

Saprazzan Skerry

Saprazzan Skerry enters tapped with two depletion counters on it.
{T}, Remove a depletion counter from Saprazzan Skerry: Add {U}{U}. If there are no depletion counters on Saprazzan Skerry, sacrifice it.

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.

Burnt Offering

As an additional cost to cast this spell, sacrifice a creature.
Add X mana in any combination of {B} and/or {R}, where X is the sacrificed creature's mana value.

Rolling Thunder

Rolling Thunder deals X damage divided as you choose among any number of targets.

Sulfur Vent

Sulfur Vent enters tapped.
{T}: Add {B}.
{T}, Sacrifice Sulfur Vent: Add {U}{R}.

Dark Ritual

Rush of Knowledge

Draw cards equal to the highest mana value among permanents you control.

Ancient Spring

Ancient Spring enters tapped.
{T}: Add {U}.
{T}, Sacrifice Ancient Spring: Add {W}{B}.

Energy Tap

Tap target untapped creature you control. If you do, add an amount of {C} equal to that creature's mana value.