Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Energy Arc

Untap any number of target creatures. Prevent all combat damage that would be dealt to and dealt by those creatures this turn.

Ashnod's Altar

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Rings of Brighthearth

Whenever you activate an ability, if it isn't a mana ability, you may pay {2}. If you do, copy that ability. You may choose new targets for the copy.

Merieke Ri Berit

Merieke Ri Berit doesn't untap during your untap step.
{T}: Gain control of target creature for as long as you control Merieke Ri Berit. When Merieke Ri Berit leaves the battlefield or becomes untapped, destroy that creature. It can't be regenerated.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Mystic Remora

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Contaminated Landscape

{T}: Add {C}.
{T}, Sacrifice Contaminated Landscape: Search your library for a basic Plains, Island, or Swamp card, put it onto the battlefield tapped, then shuffle.
Cycling {W}{U}{B} ({W}{U}{B}, Discard this card: Draw a card.)

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Mikaeus, the Lunarch

Mikaeus, the Lunarch enters with X +1/+1 counters on it.
{T}: Put a +1/+1 counter on Mikaeus.
{T}, Remove a +1/+1 counter from Mikaeus: Put a +1/+1 counter on each other creature you control.

Pentarch Paladin

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
As Pentarch Paladin enters, choose a color.
{W}{W}, {T}: Destroy target permanent of the chosen color.

Aphetto Alchemist

{T}: Untap target artifact or creature.
Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Sol Ring

Halo Fountain

{W}, {T}, Untap a tapped creature you control: Create a 1/1 green and white Citizen creature token.
{W}{W}, {T}, Untap two tapped creatures you control: Draw a card.
{W}{W}{W}{W}{W}, {T}, Untap fifteen tapped creatures you control: You win the game.

Spell Pierce

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

Adarkar Valkyrie

Flying, vigilance
{T}: When target creature other than Adarkar Valkyrie dies this turn, return that card to the battlefield under your control.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Coffin Queen

You may choose not to untap Coffin Queen during your untap step.
{2}{B}, {T}: Put target creature card from a graveyard onto the battlefield under your control. When Coffin Queen becomes untapped or you lose control of Coffin Queen, exile that creature.

Command Tower

Sokrates, Athenian Teacher

Defender
Sokrates, Athenian Teacher has hexproof as long as it's untapped.
Sokratic Dialogue — {T}: Until end of turn, target creature gains "If this creature would deal combat damage to a player, prevent that damage. This creature's controller and that player each draw half that many cards, rounded down."

Weathered Wayfarer

{W}, {T}: Search your library for a land card, reveal it, put it into your hand, then shuffle. Activate only if an opponent controls more lands than you.

Unctus, Grand Metatect

Other blue creatures you control have "Whenever this creature becomes tapped, draw a card, then discard a card."
Other artifact creatures you control get +1/+1.
{U/P}: Until end of turn, target creature you control becomes a blue artifact in addition to its other colors and types. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

Robaran Mercenaries

Vigilance
Robaran Mercenaries has all activated abilities of all legendary creatures you control.

Witch-Blessed Meadow

As Witch-Blessed Meadow enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {W}.

Witch Enchanter

When Witch Enchanter enters, destroy target artifact or enchantment an opponent controls.

Witch Enchanter // Witch-Blessed Meadow

Thousand-Year Elixir

You may activate abilities of creatures you control as though those creatures had haste.
{1}, {T}: Untap target creature.

Evil Twin

You may have Evil Twin enter as a copy of any creature on the battlefield, except it has "{U}{B}, {T}: Destroy target creature with the same name as this creature."

Patriar's Seal

{T}: Add one mana of any color.
{1}, {T}: Untap target legendary creature you control.

Land Tax

At the beginning of your upkeep, if an opponent controls more lands than you, you may search your library for up to three basic land cards, reveal them, put them into your hand, then shuffle.