Leading Performance

Choose two letters. Put a +1/+1 counter on each creature you control whose name begins with either of the chosen letters.

Meddling Kids

As Meddling Kids enters, choose a word with four or more letters.
Spells with the chosen word in their text box can't be cast.

Abstract Iguanart

Whenever you cast a spell, note the first letter of its artist's name. If that letter wasn't already noted, put a +1/+1 counter on Abstract Iguanart.

Alpha Guard

When Alpha Guard enters, choose a letter.
{T}: Untap another target permanent whose name starts with the chosen letter.

Rings a Bell

As Rings a Bell enters, choose a word with four or more letters.
After you say the chosen word for the first time each turn, an opponent may ring or imitate a bell within five seconds. When no opponent does, draw a card.

Bloodletter

When the names of three or more nonland permanents begin with the same letter, sacrifice Bloodletter. If you do, it deals 2 damage to each creature and each player.

Decisions, Decisions

Reveal the top three cards of your library, then choose a consonant. (Y counts.) Put each card that has the chosen letter in the first word of its name from among them into your hand and the rest on the bottom of your library in any order.

Now I Know My ABC's

At the beginning of your upkeep, if you control permanents with names that include all twenty-six letters of the English alphabet, you win the game.

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.)

Letter Bomb

When Letter Bomb enters, sign it and shuffle it into target player's library. That player reveals each card they draw until they draw Letter Bomb. When that player draws Letter Bomb, it deals 19½ damage to them.