As Mirrodin Besieged enters, choose Mirran or Phyrexian. • Mirran — Whenever you cast an artifact spell, create a 1/1 colorless Myr artifact creature token. • Phyrexian — At the beginning of your end step, draw a card, then discard a card. Then if there are fifteen or more artifact cards in your graveyard, target opponent loses the game.
Sacrifice Cursecatcher: Counter target instant or sorcery spell unless its controller pays {1}. 1/1
Counter target instant or sorcery spell unless its controller pays {1}. Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)
At the beginning of each player’s draw step, that player draws an additional card. 1/3
As Vesuvan Shapeshifter enters or is turned face up, you may choose another creature on the battlefield. If you do, until Vesuvan Shapeshifter is turned face down, it becomes a copy of that creature, except it has “At the beginning of your upkeep, you may turn this creature face down.” Morph {1}{U} 0/0
Enchant player At the beginning of enchanted player’s first upkeep each turn, that player gets an additional upkeep step after this step.
+2: Each player draws a card. −1: Target player draws a card. −10: Target player mills twenty cards. Loyalty: 3
Face-down creatures get +1/+1. {2}{U}: Turn target face-down creature face up. 3/4
If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield. You may cast spells as though they had flash.
Search target opponent’s library for an artifact, creature, enchantment, or land card. Put that card onto the battlefield under your control. Then that player shuffles. Epic (For the rest of the game, you can’t cast spells. At the beginning of each of your upkeeps, copy this spell except for its epic ability. You may choose a new target for the copy.)
When Denizen of the Deep enters, return each other creature you control to its owner’s hand. 11/11
Choose a card name. Target player reveals cards from the top of their library until a card with that name is revealed. If it is, that player puts the rest of the revealed cards into their graveyard and puts the card with the chosen name on top of their library. Otherwise, the player shuffles.
Flash At the beginning of each player’s draw step, that player draws an additional card.
Pitch the titles of up to X holiday-themed sequels to target spell. Copy that spell for each title pitched, except the copy has that name. You may choose new targets for the copies. (Simply adding numbers isn’t festive enough.)