Katerina of Myra's Marvels

As Katerina of Myra's Marvels enters, choose a letter.
Whenever you cast a spell whose name begins with the chosen letter, create a white 2/2 Cat creature token with flying.
Partner (You can have two commanders if they both have partner.)

Do-It-Yourself Seraph

Flying
Whenever Do-It-Yourself Seraph attacks, you may search your library for an artifact card, exile it, then shuffle.
Do-It-Yourself Seraph has the text box of each card exiled with Do-It-Yourself Seraph in addition to its own.

Spike, Tournament Grinder

({B/P} can be paid with either {B} or 2 life.)
{B/P}{B/P}{B/P}{B/P}: Reveal a card you own from outside the game that has been banned or restricted in a Constructed format and put it into your hand.

Enter the Dungeon

Players play a Magic subgame under the table, starting at 5 life and using their libraries as their decks. The winner searches their library for two cards, puts those cards into their hand, then shuffles.

Scrap Trawler

Whenever Scrap Trawler or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

Lurrus of the Dream-Den

Companion — Each permanent card in your starting deck has mana value 2 or less. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Lifelink
Once during each of your turns, you may cast a permanent spell with mana value 2 or less from your graveyard.

Prototype Portal

Imprint — When Prototype Portal enters, you may exile an artifact card from your hand.
{X}, {T}: Create a token that's a copy of the exiled card. X is the mana value of that card.

The Big Top

{T}: Add one mana of any color that appears on your top. (A top is an outerwear garment worn on the upper body.)

Necro-Impotence

Skip your untap step.
At the beginning of your upkeep, you may pay X life. If you do, untap X permanents.
Pay ½ life: Exile the top card of your library face down. Put that card into your hand at the beginning of the next end step.

Salvaging Station

{T}: Return target noncreature artifact card with mana value 1 or less from your graveyard to the battlefield.
Whenever a creature dies, you may untap Salvaging Station.

Standard Procedure

{1}, Reveal Standard Procedure from your hand: Choose an instant or sorcery card with mana value 3 or less currently legal in the Standard format. Standard Procedure becomes that card until end of turn.

Booster Tutor

Open a sealed Magic booster pack, reveal the cards, and put one of them into your hand. (Remove that card from your deck before beginning a new game.)

Mindslaver

{4}, {T}, Sacrifice Mindslaver: You control target player during that player's next turn. (You see all cards that player could see and make all decisions for the player.)

Look at Me, I'm the DCI

Ban a card other than a basic land card for the rest of the match. (All cards with that name in any zone or sideboard are removed from the match.)

Ladies' Knight

Flying
Spells cast by players wearing at least one item of women's clothing cost {1} less to cast. (You can define women's clothing as you see fit. Be reasonable.)

Razor Hippogriff

Flying
When Razor Hippogriff enters, return target artifact card from your graveyard to your hand. You gain life equal to that card's mana value.

Cheap Ass

Park Map

{1}, Sacrifice Park Map: Search your library for a land card that doesn't have the same art as a permanent you control, reveal it, put it into your hand, then shuffle.

R&D's Secret Lair

Play cards as written. Ignore all errata.
{T}: Add {C}. (This mana is still added to your mana pool.)

Impounding Lot-Bot

When Impounding Lot-Bot enters, you may say "INCARCERATE!" in a robot voice. If you do, exile another target artifact or enchantment until Impounding Lot-Bot leaves the battlefield.

Gleemax

You choose all targets for all spells and abilities.

Ashnod's Coupon

{T}, Sacrifice Ashnod's Coupon: Target player gets you target drink. You pay any costs for the drink.

Wordmail

Enchant creature
Enchanted creature gets +1/+1 for each word in its name.

Keen Duelist

At the beginning of your upkeep, you and target opponent each reveal the top card of your library. You each lose life equal to the mana value of the card revealed by the other player. You each put the card you revealed into your hand.

Animate Graveyard

Enchant your graveyard
Enchanted graveyard is a creature on the battlefield with base power and toughness each equal to the number of cards in it. It has the text boxes of all creature cards in it. It's still a graveyard.
If enchanted graveyard would leave the battlefield, instead exile Animate Graveyard.

Organ Harvest

Your team may sacrifice any number of creatures. For each creature sacrificed this way, you add {B}{B}.

Over My Dead Bodies

Creature cards in graveyards can attack and block as though they were on the battlefield, can block or be blocked only by creature cards in graveyards, are Zombies in addition to their other types, and have undeathtouch. (If they would deal damage to a creature card, exile that creature card instead.)
Creature cards in your graveyard have haste.

Chaos Confetti

{4}, {T}: Tear Chaos Confetti into pieces. Throw the pieces onto the battlefield from a distance of at least five feet. Destroy each permanent that a piece touches. Remove the pieces from the game.

Form of the Approach of the Second Sun

When this enchantment enters, you gain 7 life. You become a card until you leave your library or that library is shuffled. Put yourself seventh from the top, balancing the cards on top of you on your head.
When you draw yourself, you win the game.
When one or more cards fall off your head, exile them and all cards on your head, then sacrifice this enchantment.

Deadhead

{0}: Return Deadhead from your graveyard to the battlefield. Activate only if an opponent isn't touching their hand (of cards).

Summon the Pack

Open a sealed Magic booster pack, reveal the cards, and put all creature cards revealed this way onto the battlefield under your control. They're Zombies in addition to their other types. (Remove those cards from your deck before beginning a new game.)

Charm School

As Charm School enters, choose a color and balance Charm School on your head.
Prevent all damage that would be dealt to you by sources of the chosen color.
When Charm School falls off your head, sacrifice Charm School.

Grand Marshal Macie

You may choose not to untap Grand Marshal Macie during your untap step. If you do, put a pause counter on it, then you lose 1 life for each pause counter on it.
Whenever Macie becomes untapped, remove all pause counters from it.
{2}, {T}: Choose an "until end of turn" or "this turn" effect. As long as Macie remains tapped, that effect doesn't end.

By Gnome Means

{1}{W}, Remove a counter from a permanent you control: Create a 1/1 colorless Gnome artifact creature token.
{1}{W}, Sacrifice an artifact: Choose any kind of counter a printed card refers to, then put one of that counter on target permanent.

Kindslaver

{5}, {T}, Sacrifice Kindslaver: A person outside the game controls target player during that player's next turn. Neither player may advise that person until the end of that turn.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Urza's Saga gains "{T}: Add {C}."
II — Urza's Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This creature gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Pointy Finger of Doom

{3}, {T}: Spin Pointy Finger of Doom in the middle of the table so that it rotates completely at least once, then destroy the closest permanent the finger points to.

Nocturno of Myra's Marvels

As Nocturno of Myra's Marvels enters, choose a word with five or more letters.
Whenever you cast a spell with the chosen word in its rules text, you draw a card and you lose 2 life.
Partner (You can have two commanders if both have partner.)

Split Screen

When Split Screen enters, shuffle your library and deal it into four libraries. If anything refers to your library, choose one of your libraries for it.
Play with your libraries' top cards revealed.
When Split Screen leaves the battlefield, shuffle your libraries together.