Aurelia, the Law Above

Flying, vigilance, haste
Whenever a player attacks with three or more creatures, you draw a card.
Whenever a player attacks with five or more creatures, Aurelia deals 3 damage to each of your opponents and you gain 3 life.

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Ogre Marauder

Whenever this creature attacks, it gains "this creature can't be blocked" until end of turn unless defending player sacrifices a creature of their choice.

Kazuul, Tyrant of the Cliffs

Whenever a creature an opponent controls attacks, if you're the defending player, create a 3/3 red Ogre creature token unless that creature's controller pays {3}.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Hissing Miasma

Whenever a creature attacks you, its controller loses 1 life.

Boros Signet

Overclocked Electromancer

At the beginning of combat on your turn, you may pay {E}{E}{E}. If you do, put a +1/+1 counter on this creature.
Whenever this creature attacks, double its power until end of turn.
Whenever this creature deals combat damage to a creature, if that creature was dealt excess damage this turn, you get X {E}, where X is that excess damage.

Bone Mask

{2}, {T}: The next time a source of your choice would deal damage to you this turn, prevent that damage. Exile cards from the top of your library equal to the damage prevented this way.

Brimaz, King of Oreskos

Vigilance
Whenever Brimaz attacks, create a 1/1 white Cat Soldier creature token with vigilance that's attacking.
Whenever Brimaz blocks a creature, create a 1/1 white Cat Soldier creature token with vigilance that's blocking that creature.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Anim Pakal, Thousandth Moon

Whenever you attack with one or more non-Gnome creatures, put a +1/+1 counter on Anim Pakal, then create X 1/1 colorless Gnome artifact creature tokens that are tapped and attacking, where X is the number of +1/+1 counters on Anim Pakal.

Breena, the Demagogue

Flying
Whenever a player attacks one of your opponents, if that opponent has more life than another of your opponents, that attacking player draws a card and you put two +1/+1 counters on a creature you control.

Caltrops

Whenever a creature attacks, this artifact deals 1 damage to it.

Talisman of Hierarchy

{T}: Add {C}.
{T}: Add {W} or {B}. This artifact deals 1 damage to you.

Sol Ring

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Deflecting Palm

The next time a source of your choice would deal damage to you this turn, prevent that damage. If damage is prevented this way, Deflecting Palm deals that much damage to that source's controller.

Orzhov Signet

Summon: Knights of Round

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after V.)
I, II, III, IV — Create three 2/2 white Knight creature tokens.
V — Ultimate End — Other creatures you control get +2/+2 until end of turn. Put an indestructible counter on each of them.
Indestructible

Powerstone Minefield

Whenever a creature attacks or blocks, this enchantment deals 2 damage to it.

Ghostly Prison

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. This artifact deals 1 damage to you.

Calculating Lich

Menace
Whenever a creature attacks one of your opponents, that player loses 1 life.

Brash Taunter

Indestructible
Whenever this creature is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: This creature fights another target creature.

Creepy Doll

Indestructible
Whenever this creature deals combat damage to a creature, flip a coin. If you win the flip, destroy that creature.

Rakdos Signet

Death Kiss

Whenever a creature an opponent controls attacks one of your opponents, double its power until end of turn.
{X}{X}{R}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
When this creature becomes monstrous, goad up to X target creatures your opponents control.

Shadowbane

The next time a source of your choice would deal damage to you and/or creatures you control this turn, prevent that damage. If damage from a black source is prevented this way, you gain that much life.

Barbed Servitor

Indestructible
When this creature enters, suspect it. (It has menace and can't block.)
Whenever this creature deals combat damage to a player, you draw a card and you lose 1 life.
Whenever this creature is dealt damage, target opponent loses that much life.

Emberwilde Captain

When this creature enters, you become the monarch.
Whenever an opponent attacks you while you're the monarch, this creature deals damage to that player equal to the number of cards in their hand.

Mangara, the Diplomat

Lifelink
Whenever an opponent attacks with creatures, if two or more of those creatures are attacking you and/or planeswalkers you control, draw a card.
Whenever an opponent casts their second spell each turn, draw a card.

Phyrexian Dragon Engine

Double strike
When this creature enters from your graveyard, you may discard your hand. If you do, draw three cards.
Unearth {3}{R}{R}
(Melds with Mishra, Claimed by Gix.)

Reverse Damage

The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.

Mishra, Claimed by Gix

Whenever you attack, each opponent loses X life and you gain X life, where X is the number of attacking creatures. If Mishra, Claimed by Gix and a creature named Phyrexian Dragon Engine are attacking, and you both own and control them, exile them, then meld them into Mishra, Lost to Phyrexia. It enters tapped and attacking.

Stuffy Doll

Indestructible
As this creature enters, choose a player.
Whenever this creature is dealt damage, it deals that much damage to the chosen player.
{T}: This creature deals 1 damage to itself.

Gisa's Favorite Shovel

Equipped creature gets +2/+0 and has menace.
Whenever equipped creature attacks, defending player sacrifices a creature of their choice. If they do, you create a Walker token.
Equip {4}

Righteous Cause

Whenever a creature attacks, you gain 1 life.

Mogis, God of Slaughter

Indestructible
As long as your devotion to black and red is less than seven, Mogis isn't a creature.
At the beginning of each opponent's upkeep, Mogis deals 2 damage to that player unless they sacrifice a creature of their choice.

Curse of the Forsaken

Enchant player
Whenever a creature attacks enchanted player, its controller gains 1 life.

Honorable Passage

The next time a source of your choice would deal damage to any target this turn, prevent that damage. If damage from a red source is prevented this way, Honorable Passage deals that much damage to the source's controller.

Darksteel Reactor

Indestructible (Effects that say "destroy" don't destroy this artifact.)
At the beginning of your upkeep, you may put a charge counter on this artifact.
When this artifact has twenty or more charge counters on it, you win the game.

Arcane Signet

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

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. This artifact deals 1 damage to you.

Eye for an Eye

The next time a source of your choice would deal damage to you this turn, instead that source deals that much damage to you and Eye for an Eye deals that much damage to that source's controller.

General's Regalia

{3}: The next time a source of your choice would deal damage to you this turn, that damage is dealt to target creature you control instead.

The Millennium Calendar

Whenever you untap one or more permanents during your untap step, put that many time counters on The Millennium Calendar.
{2}, {T}: Double the number of time counters on The Millennium Calendar.
When there are 1,000 or more time counters on The Millennium Calendar, sacrifice it and each opponent loses 1,000 life.

Kardur, Doomscourge

When Kardur enters, until your next turn, creatures your opponents control attack each combat if able and attack a player other than you if able.
Whenever an attacking creature dies, each opponent loses 1 life and you gain 1 life.

Jade Monolith

{1}: The next time a source of your choice would deal damage to target creature this turn, that source deals that damage to you instead.

Anointer of Valor

Flying
Whenever a creature attacks, you may pay {3}. When you do, put a +1/+1 counter on that creature.

Raid Bombardment

Whenever a creature you control with power 2 or less attacks, this enchantment deals 1 damage to the player or planeswalker that creature is attacking.

Aurification

Whenever a creature deals damage to you, put a gold counter on it.
Each creature with a gold counter on it is a Wall in addition to its other creature types and has defender. (Those creatures can't attack.)
When this enchantment leaves the battlefield, remove all gold counters from all creatures.

Isshin, Two Heavens as One

If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Audacious Thief

Whenever this creature attacks, you draw a card and you lose 1 life.

Unwinding Clock

Untap all artifacts you control during each other player's untap step.

Darksteel Myr

Indestructible (Damage and effects that say "destroy" don't destroy this creature. If its toughness is 0 or less, it's still put into its owner's graveyard.)

Darksteel Plate

Indestructible
Equipped creature has indestructible.
Equip {2}

Mechanized Warfare

If a red or artifact source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 1 instead.

Dolmen Gate

Prevent all combat damage that would be dealt to attacking creatures you control.

Windborn Muse

Flying
Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Impulsive Maneuvers

Whenever a creature attacks, flip a coin. If you win the flip, the next time that creature would deal combat damage this turn, it deals double that damage instead. If you lose the flip, the next time that creature would deal combat damage this turn, prevent that damage.

Reflect Damage

The next time a source of your choice would deal damage this turn, that damage is dealt to that source's controller instead.

Nefarox, Overlord of Grixis

Flying
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
Whenever Nefarox attacks alone, defending player sacrifices a creature of their choice.

Invulnerability

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
The next time a source of your choice would deal damage to you this turn, prevent that damage.

Rhystic Circle

{1}: Any player may pay {1}. If no one does, the next time a source of your choice would deal damage to you this turn, prevent that damage.

Intervention Pact

The next time a source of your choice would deal damage to you this turn, prevent that damage. You gain life equal to the damage prevented this way.
At the beginning of your next upkeep, pay {1}{W}{W}. If you don't, you lose the game.