Add .
Threshold — Add instead if there are seven or more cards in your graveyard.

All Cats you control are Dogs in addition to their other types.
All Dogs you control are Cats in addition to their other types.
Cats and Dogs you control have haste.

Cast this spell only during your turn.
Take an extra turn after this one if an opponent cast a blue spell this turn.

Equipped creature has ", : This creature deals 1 damage to any target" and "Whenever a creature dies, untap this creature."
Whenever a Shaman creature enters, you may attach this Equipment to it.
Equip

Equipped creature has flying.
Equip
Equipment swap (: Exchange this Equipment with an Equipment card in your hand. If this Equipment was attached to a creature, attach the new Equipment to that creature.)

Draw four cards, then discard three cards at random.

When this enchantment enters, exile all graveyards.
If a card or token would be put into a graveyard from anywhere, exile it instead.

Destroy target artifact, enchantment, emblem, or gameplay tracker. (Trackers include play aids such as dungeons, city's blessing, and monarch. When you destroy it, the associated object or designation is removed from the game.)

: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Whenever a spell you control causes you to gain card advantage, each opponent loses 2 life. (You gain card advantage each time a spell you control resolves and you end up having more cards relative to your opponents than before that spell resolved. Divination, Annihilate, and Wrath of God can all be card advantage. And remember: tokens aren't cards!)

Destroy target artifact.
Flashback (You may cast this card from your graveyard for its flashback cost. Then exile it.)

, Sacrifice an artifact: Target player mills three cards.
Whenever an artifact enters, you may untap this artifact.

You have no maximum hand size.
: Add .

You may draw cards from anywhere in your library. (You don't get to look at them or reorder them while doing so.)
When Heart of a Duelist enters the battlefield, draw a card.

If a player would draw a card except the first one they draw in each of their draw steps, that player discards a card instead. If the player discards a card this way, they draw a card. If the player doesn't discard a card this way, they mill a card.

Exile target creature if it has any abilities other than keywords. (Flying, protection, and partner are all keywords. See rule 702 for details. Landfall and scry aren't keywords; they're an ability word and a keyword action respectively. Yes, there's a difference.)

At the beginning of each player's upkeep, that player chooses target player who controls more creatures than they do and is their opponent. The first player may reveal cards from the top of their library until they reveal a creature card. If the first player does, that player puts that card onto the battlefield and all other cards revealed this way into their graveyard.

If this spell is the first spell you've cast this game, you may cast it without paying its mana cost.
Look at the top five cards of your library. You may reveal a creature or land card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Imprint — When this artifact enters, you may exile an instant card with mana value 2 or less from your hand.
, : You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

: Untap target creature.

Each player can't draw more than one card each turn.

Look at the top three cards of your library. Put one of them into your hand, put one of them on the bottom of your library, and exile one of them. You may play the exiled card this turn.

Put a random creature from a random graveyard into play under your control. Call from the Grave deals to you an amount of damage equal to that creature's casting cost.

Flying
Each player can't cast more than one spell each turn.
Nonbasic lands your opponents control enter tapped.

Banding (Just ask around until you find someone who knows.)
Creature spells you cast with banding cost less to cast.
Whenever two or more creatures you control attack in a band, each creature in that band gets +1/+1 until end of turn for each creature in that band.

This spell costs less to cast if it targets a blue spell.
Counter target spell unless its controller pays .

Each opponent can cast spells only any time they could cast a sorcery.
+1: Until your next turn, you may cast sorcery spells as though they had flash.
−3: Return up to one target artifact, creature, or enchantment to its owner's hand. Draw a card.

Each player loses a third of their life, then discards a third of the cards in their hand, then sacrifices a third of the creatures they control of their choice, then sacrifices a third of the lands they control of their choice. Round up each time.

All artifacts have "At the beginning of your upkeep, sacrifice this artifact unless you pay ."

: Add .
Any time you could mulligan and this card is in your hand, you may exile all the cards from your hand, then draw that many cards. (You can do this in addition to taking mulligans.)

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Haste (This creature can attack and as soon as it comes under your control.)
At the beginning of the end step, sacrifice this creature.

Tap all lands target player controls and that player loses all unspent mana.

+2: Each player draws a card.
−1: Target player draws a card.
−10: Target player mills twenty cards.

( can be paid with one mana from a legendary source.)
Other legendary creatures you control get +1/+1 and have indestructible.

Level up (: Put a level counter on this. Level up only as a sorcery.)
LEVEL 6-11
6/6
Lifelink
LEVEL 12+
9/9
Lifelink, indestructible

Xantcha enters under the control of an opponent of your choice.
Xantcha attacks each combat if able and can't attack its owner or planeswalkers its owner controls.
: Xantcha's controller loses 2 life and you draw a card. Any player may activate this ability.