If you would lose unspent mana, that mana becomes colorless instead.

You may pay 1 life and exile a black card from your hand rather than pay this spell's mana cost.
Distribute two -2/-1 counters among one or two target creatures.

Whenever an opponent plays a land, put a +1/+1 counter on this creature.

Whenever you tap a Forest for mana, add an additional .
+1: Put three +1/+1 counters on up to one target noncreature land you control. Untap it. It becomes a 0/0 Elemental creature with vigilance and haste that's still a land.
−8: You get an emblem with "Lands you control have indestructible." Search your library for any number of Forest cards, put them onto the battlefield tapped, then shuffle.

Return target creature card from your graveyard to the battlefield tapped.
Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Thundering Mightmare is paired with another creature, each of those creatures has "Whenever an opponent casts a spell, put a +1/+1 counter on this creature."

Choose one —
• Burn Down the House deals 5 damage to each creature and each planeswalker.
• Create three 1/1 red Devil creature tokens with "When this token dies, it deals 1 damage to any target." They gain haste until end of turn.

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Sliver spells you cast have cascade.

Flying
Discard a card: This creature gains hexproof until end of turn. Tap it.
Whenever this creature attacks, scry 3.

Whenever Karn blocks or becomes blocked, it gets -4/+4 until end of turn.
: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value until end of turn.

Lifelink
At the beginning of your end step, if you gained life this turn, you may pay X life, where X is the amount of life you gained this turn. If you do, create an X/X black Demon creature token with flying.

You may cast this spell as though it had flash if you pay more to cast it. (You may cast it any time you could cast an instant.)
Destroy all creatures. They can't be regenerated.

Flash (You may cast this spell any time you could cast an instant.)
Flying
Spells you cast with mana value 5 or greater cost less to cast and can't be countered.

You may cast up to two instant and/or sorcery spells with total mana value 6 or less from your graveyard and/or hand without paying their mana costs. If those spells would be put into your graveyard, exile them instead. Exile Invoke Calamity.

Destroy all artifacts, then Structural Assault deals damage to each creature equal to the number of artifacts that were put into graveyards from the battlefield this turn.

At the beginning of your upkeep, you gain X life, where X is the number of cards in your hand minus 4.
Whenever you gain life, each Advisor, Artificer, and Monk you control gains vigilance and gets +X/+0 until end of turn, where X is the amount of life you gained.
Tap three untapped Advisors, Artificers, and/or Monks you control: Draw a card.

This spell costs less to cast for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)
Search your library for a card, put it into your hand, then shuffle. If you have a full party, you may cast a spell with mana value 4 or less from your hand without paying its mana cost.

Flying
Whenever you cast a noncreature spell, creatures you control gain lifelink until end of turn.

Enchant player
At the beginning of enchanted player's upkeep, any number of target players other than that player each draw cards equal to the number of Curses attached to that player.

Each player puts a vow counter on a creature they control and sacrifices the rest. Each of those creatures can't attack you or planeswalkers you control for as long as it has a vow counter on it.

Each creature deals damage to itself equal to its power.

Whenever this creature enters or attacks, put a slime counter on up to one other target creature.
Non-Horror creatures with slime counters on them lose all abilities and have base power and toughness 2/2.

Necrogoyf's power is equal to the number of creature cards in all graveyards.
At the beginning of each player's upkeep, that player discards a card.
Madness (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Constellation — Whenever this creature or another enchantment you control enters, creatures your opponents control get -1/-1 until end of turn.

: Create a 1/1 colorless Sliver creature token.

Draw a card for each creature you control.
Ferocious — You gain 4 life for each creature you control with power 4 or greater.

Flash
If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Whenever an opponent draws a card, you may pay . If you do, draw a card.

: Create a 1/1 green Insect creature token.

Heroic — Whenever you cast a spell that targets Anthousa, up to three target lands you control each become 2/2 Warrior creatures until end of turn. They're still lands.

When this creature dies, create two 2/2 green Ooze creature tokens. They have "When this token dies, create two 1/1 green Ooze creature tokens."

Prevent all combat damage that would be dealt to you this turn. For each 1 damage prevented this way, create a 2/1 white and black Inkling creature token with flying.

Flying, haste
You may cast sorcery spells as though they had flash. (You may cast them any time you could cast an instant.)

Demonstrate (When you cast this spell, you may copy it. If you do, choose an opponent to also copy it.)
Shuffle your library, then reveal cards from the top of it until you reveal a nonland card. Exile that card and put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost.

Bestow (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached.)
Flying, first strike
Enchanted creature gets +4/+4 and has flying and first strike.

When this creature enters, put a shield counter on target noncommander creature you don't control. You gain control of that creature for as long as it has a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)