Have

Maga, Traitor to Mortals

Maga, Traitor to Mortals enters the battlefield with X +1/+1 counters on it.
When Maga enters the battlefield, target player loses life equal to the number of +1/+1 counters on it.

Blood Moon

Graven Cairns

{T}: Add {C}.
{B/R}, {T}: Add {B}{B}, {B}{R}, or {R}{R}.

Goldhound

First strike
Menace (This creature can't be blocked except by two or more creatures.)
{T}, Sacrifice Goldhound: Add one mana of any color.

Beseech the Queen

({2/B} can be paid with any two mana or with {B}. This card's mana value is 6.)
Search your library for a card with mana value less than or equal to the number of lands you control, reveal it, put it into your hand, then shuffle.

Rowan, Scion of War

Menace
{T}: Spells you cast this turn that are black and/or red cost {X} less to cast, where X is the amount of life you lost this turn. Activate only as a sorcery.

Nihil Spellbomb

{T}, Sacrifice Nihil Spellbomb: Exile target player's graveyard.
When Nihil Spellbomb is put into a graveyard from the battlefield, you may pay {B}. If you do, draw a card.

Manamorphose

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

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Swamp

Blood Crypt

({T}: Add {B} or {R}.)
As Blood Crypt enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Step Through

Return two target creatures to their owners' hands.
Wizardcycling {2} ({2}, Discard this card: Search your library for a Wizard card, reveal it, put it into your hand, then shuffle.)

Crackle with Power

Crackle with Power deals five times X damage to each of up to X targets.

Fatal Push

Destroy target creature if it has mana value 2 or less.
Revolt — Destroy that creature if it has mana value 4 or less instead if a permanent you controlled left the battlefield this turn.

Haywire Mite

When Haywire Mite dies, you gain 2 life.
{G}, Sacrifice Haywire Mite: Exile target noncreature artifact or noncreature enchantment.

Blackcleave Cliffs

Blackcleave Cliffs enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {B} or {R}.

Goryo's Vengeance

Return target legendary creature card from your graveyard to the battlefield. That creature gains haste. Exile it at the beginning of the next end step.
Splice onto Arcane {2}{B} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Boseiju, Who Shelters All

Boseiju, Who Shelters All enters the battlefield tapped.
{T}, Pay 2 life: Add {C}. If that mana is spent on an instant or sorcery spell, that spell can't be countered.

Inquisition of Kozilek

Target player reveals their hand. You choose a nonland card from it with mana value 3 or less. That player discards that card.

Marsh Flats

{T}, Pay 1 life, Sacrifice Marsh Flats: Search your library for a Plains or Swamp card, put it onto the battlefield, then shuffle.

Overgrown Tomb

({T}: Add {B} or {G}.)
As Overgrown Tomb enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Plunge into Darkness

Choose one —
• Sacrifice any number of creatures. You gain 3 life for each sacrificed creature.
• Pay X life, then look at the top X cards of your library. Put one of those cards into your hand and exile the rest.
Entwine {B} (Choose both if you pay the entwine cost.)

Spellskite

{U/P}: Change a target of target spell or ability to Spellskite. ({U/P} can be paid with either {U} or 2 life.)

Magus of the Moon

Verdant Catacombs

{T}, Pay 1 life, Sacrifice Verdant Catacombs: Search your library for a Swamp or Forest card, put it onto the battlefield, then shuffle.

Hex Parasite

{X}{B/P}: Remove up to X counters from target permanent. For each counter removed this way, Hex Parasite gets +1/+0 until end of turn. ({B/P} can be paid with either {B} or 2 life.)

Shivan Devastator

Flying, haste
Shivan Devastator enters the battlefield with X +1/+1 counters on it.