Tomenado

Creature -- Elemental (R)
Trample, haste
If Tomenado would deal combat damage to a player, instead prevent that damage and draw that many cards.
At the beginning of the end step, sacrifice Tomenado.
6/1

Magus of Knowledge
Creature - Human Wizard (M)
At the beginning of your upkeep, if you have no cards in your hand, draw 7 cards.
1/1

Neurotic Break

Instant (U)
Counter target spell unless its controller mills twenty cards.

Edit: This, as it turns out, is not the Alphabet game.

Meekling
Creature ─ Faerie Rogue (C)
Flying, deathtouch, lifelink
Meekling loses its keyword abilities if an opponent controls a creature with power 2 or greater.
1/1

Escorted Courtier
Creature — Faerie Noble (U)
Flying
When Escorted Courtier enters the battlefield, each opponent may bargain. For each opponent who doesn't, create a 1/1 blue Faerie creature token with flying and "This creature can't block creatures without flying."
2/1

Siphoning Predator

Creature -- Vampire (R)
Flying, lifelink
Other creatures you control get -1/-1.
Siphoning Predator gets +1/+1 for each other creature you control.
3/3

Curse of Parasitic Power
Enchantment - Aura Curse (M)
Enchant opponent.
At the beginning of your upkeep, you gain 2 life for each card in their hand unless they discard their hand. If they do, discard your hand.
Pay 1 life: Draw a card. You and enchanted opponent may activate this ability.

Not sure if adding symmetry to Necropotence balances it, but I know it at least makes it less broken.

Hellhound of Haxes

Creature -- Elemental Dog (C)
Momentum — Whenever Hellhound of Haxes attacks, if you also attacked during your last turn, Hellhound of Haxes deals 2 damage to defending player or permanent.
2/2

Earth Spike
Sorcery (U)
Earth Spike deals damage to target creature equal to the number of +1/+1 counters on it.

Unassuming Wish
Sorcery (R)
Choose one—

• Exile the top five cards on your library. You may play those cards this turn.
• Exile the top two cards on your library. You may play those cards until end of your next turn.
• At the beginning of your next upkeep, shuffle, then exile cards from the top of your library until you exile a nonland card. You may cast the nonland card without paying its mana cost.

Millet, Cell Leader
Legendary Creature ─ Goblin Rebel (M)
Haste, prowess
Whenever you exile a card from the top of your library, add X where X is the number of cards exiled in this way.
2/2

Plant a Seed

Sorcery (C)
Search your library for a basic Forest card, put it onto the battlefield, then shuffle.
, Exile Plant a Seed from your graveyard: Create a 6/6 green Treefolk creature token with reach. Activate this ability only if you control six or more Forests.

Stop and Smell the Roses
Enchantment (U)
At the beginning of your end step, if you have one or more unused land plays, create a 1/1 green Plant creature token.
Some moments are too lovely for anything else.

Rose By Any Other Name
Creature — Plant
You may have Rose By Any Other Name enter the battlefield as a copy of any creature you control on the battlefield, except its base power and toughness is 0/0, its name is Rose By Any Other Name, and it enters the battlefield with X +1/+1 counters, where X is that creature's toughness.
0/0

Apex Carnivore
Creature ─ Elemental (M)
Trample
Sacrifice a nontoken creature with no abilities: Return Apex Carnivore from your graveyard to the battlefield.
6/6
In war they turned from prey to sacrifice.

Multicolor

Survival Bias
Instant (C)
Target creature you control gets +1/+1 and gains hexproof until end of turn.
Draw a card.

Unchained Lightning
Creature - Elemental (U)
Haste, trample, hexproof
6/1

Octospider

Creature -- Octopus Spider (R)
Octospider enters the battlefield with eight +1/+1 counters on it.
: You may move a +1/+1 counter from Octospider onto another target creature. When you do, tap or untap that creature.
“Some combinations are obvious.”
—Zija, Simic mutationist
0/0

Reality Marble
Enchantment (M)
When ~ enters the battlefield, exile all nonland permanents until ~ leaves the battlefield.
At the beginning of each player's upkeep, that player may create a token that is a copy of target card they own exiled with ~.

Hybrid

Embrace the Void
Instant (C)
As an additional cost to cast Embrace the Void, discard a card.
Exile target creature with converted mana cost equal to the mana value of the discarded card.
Darkness demands its price.