First strike
When Rahilda, Wanted Cutthroat deals combat damage to a player, exile a nonland card from their library at random. During any turn you attacked with a Wolf or Werewolf, you may cast that card and you may spend mana as though it were mana of any color to cast that spell.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Double strike
Spells cast from among cards you drew this turn cost less to cast.
Spells cast from among cards your opponents drew this turn cost more to cast.

At the beginning of your upkeep, look at the top two cards of your library, then put one of them into your graveyard.
Whenever a creature card is put into your graveyard from your library or hand, it perpetually gains "When this card leaves your graveyard, create a tapped 2/2 black Zombie creature token."

Flying, deathtouch
When Gutmorn, Pactbound Servant enters the battlefield, each player discards a nonland card.
Whenever a player discards a card during your turn, they choose another player. That player conjures a duplicate of that card into their hand. It perpetually gains "You may spend mana as though it were mana of any color to cast this spell."

Lifelink
Whenever this creature enters or attacks, choose a card in your hand. It perpetually gains lifelink.

At the beginning of your end step, exile up to one target creature card from your graveyard. If you do, seek a creature card with mana value equal to the mana value of that card plus one. That card perpetually gains menace.

+1: Choose a creature card in your hand. It perpetually gets +1/+1 and perpetually gains "This spell costs less to cast."
−1: Draft a card from Garruk, Wrath of the Wilds's spellbook and put it onto the battlefield.
−6: Until end of turn, creatures you control get +3/+3 and gain trample.

Reach
Other Spiders you control get +1/+2.
, Exile two cards from your graveyard: Draft a card from Ishkanah, Broodmother's spellbook.

+1: Add . Draft a card from Tibalt, Wicked Tormentor's spellbook, then exile it. Until end of turn, you may cast that card.
+1: Tibalt, Wicked Tormentor deals 4 damage to target creature or planeswalker unless its controller has Tibalt deal 4 damage to them. If they do, you may discard a card. If you do, draw a card.
−X: Create X 1/1 red Devil creature tokens with "When this creature dies, it deals 1 damage to any target."

Flying
When Geist of Regret enters the battlefield, put a random instant card from your library into your graveyard. Then put a random sorcery card from your library into your graveyard.
Whenever you cast an instant or sorcery spell from your graveyard, copy that spell. You may choose new targets for the copy.