Coils of the Medusa

Enchant creature
Enchanted creature gets +1/-1.
Sacrifice Coils of the Medusa: Destroy all non-Wall creatures blocking enchanted creature.

Chaos Moon

At the beginning of each upkeep, count the number of permanents. If the number is odd, until end of turn, red creatures get +1/+1 and whenever a player taps a Mountain for mana, that player adds an additional {R}. If the number is even, until end of turn, red creatures get -1/-1 and if a player taps a Mountain for mana, that Mountain produces colorless mana instead of any other type.

Skull Storm

When you cast this spell, copy it for each time you've cast your commander from the command zone this game.
Each opponent sacrifices a creature of their choice. Each opponent who can't loses half their life, rounded up.

Whims of the Fates

Starting with you, each player separates all permanents they control into three piles. Then each player chooses one of their piles at random and sacrifices those permanents. (Piles can be empty.)

Meditation Puzzle

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
You gain 8 life.

Rogue

Gemstone Array

{2}: Put a charge counter on Gemstone Array.
Remove a charge counter from Gemstone Array: Add one mana of any color.

Knight

Cackling Flames

Cackling Flames deals 3 damage to any target.
Hellbent — Cackling Flames deals 5 damage instead if you have no cards in hand.

Sage of Days

When Sage of Days enters, look at the top three cards of your library. You may put one of those cards back on top of your library. Put the rest into your graveyard.

Chromatic Star

{1}, {T}, Sacrifice Chromatic Star: Add one mana of any color.
When Chromatic Star is put into a graveyard from the battlefield, draw a card.

Balance

Each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice creatures the same way.

Jester's Mask

Jester's Mask enters tapped.
{1}, {T}, Sacrifice Jester's Mask: Target opponent puts the cards from their hand on top of their library. Search that player's library for that many cards. That player puts those cards into their hand, then shuffles.

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

Disappear

Enchant creature
{U}: Return enchanted creature and Disappear to their owners' hands.

Rite of Ruin

Choose an order for artifacts, creatures, and lands. Each player sacrifices one permanent of their choice of the first type, sacrifices two of their choice of the second type, then sacrifices three of their choice of the third type.

Lightning Talons

Enchant creature
Enchanted creature gets +3/+0 and has first strike. (It deals combat damage before creatures without first strike.)

Fool's Tome

{2}, {T}: Draw a card. Activate only if you have no cards in hand.

Void

Choose a number. Destroy all artifacts and creatures with mana value equal to that number. Then target player reveals their hand and discards all nonland cards with mana value equal to the number.

Mystery Key

When equipped creature deals combat damage to a player, sacrifice Mystery Key. If you do, draw three cards.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Throne of Empires

{1}, {T}: Create a 1/1 white Soldier creature token. Create five of those tokens instead if you control artifacts named Crown of Empires and Scepter of Empires.

Sunbond

Enchant creature
Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."