Main Event Horizon

As an additional cost to cast this spell, choose A through M or N through Z.
Destroy each creature whose name begins with a letter in the chosen range.

Leading Performance

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

Goblin Tutor

Roll a six-sided die. If you roll a 1, Goblin Tutor has no effect. Otherwise, search your library for the indicated card, reveal it, put it into your hand, then shuffle.
2 — A card named Goblin Tutor
3 — An enchantment
4 — An artifact
5 — A creature
6 — An instant or sorcery

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.)

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.

Stet, Draconic Proofreader

Flying
Whenever Stet, Draconic Proofreader attacks, you may exile a card from your graveyard. When you do, Stet, Draconic Proofreader deals 4 damage to any target whose name begins with the same letter as the exiled card.
{W}: Delete the first letter of target permanent or player's name until end of turn.

Goblin Cruciverbalist

Haste
When Goblin Cruciverbalist enters, create a colorless artifact token named your choice of A, E, I, O, or U.
Whenever Goblin Cruciverbalist attacks, using the first letters of the names of permanents you control, spell a word you haven't spelled this game. It gets +1/+0 until end of turn for each letter in that word.

Oddly Uneven

Choose one —
• Destroy each creature with an odd number of words in its name. (Hyphenated words are one word.)
• Destroy each creature with an even number of words in its name.