Acornelia, Fashionable Filcher

Whenever you cast a spell with a squirrel in its art, you get {A} (an acorn counter).
Whenever a Squirrel you control enters or dies, you get {A}.
{2}{B}, Pay X {A}: Target creature gets -X/-X until end of turn.
{G}, Pay X {A}: Target creature gets +X/+X until end of turn.

Farewell to Arms

As this enchantment enters, choose a hand attached to an opponent's arm.
When the chosen hand isn't behind its owner's back, sacrifice this enchantment. If you do, that player discards their hand . . . of cards. (The lawyers wouldn't let us do it the other way.)

Destroy target creature with reminder text. (Reminder text is any italicized text in parentheses that explains rules you already know.)

Eye to Eye

You and target creature's controller have a staring contest. If you win, destroy that creature.

Come Back Wrong

Destroy target creature. If a creature card is put into a graveyard this way, return it to the battlefield under your control. Sacrifice it at the beginning of your next end step.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Osteomancer Adept

Deathtouch
{T}: Until end of turn, you may cast creature spells from your graveyard by foraging in addition to paying their other costs. If you cast a spell this way, that creature enters with a finality counter on it. (To forage, exile three cards from your graveyard or sacrifice a Food. If a creature with a finality counter on it would die, exile it instead.)

When Fluffy Bunnies Attack

Target creature gets -X/-X until end of turn, where X is the number of times the letter of your choice appears in that creature's name.

Booster Tutor

Open a sealed Magic booster pack, reveal the cards, and put one of them into your hand. (Remove that card from your deck before beginning a new game.)

Dark Petition

Search your library for a card, put that card into your hand, then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, add {B}{B}{B}.