This seems like a fairly simple and common relational problem that is solved by a cross-reference table. For example:
CREATE TABLE dbo.Cards (
id INT NOT NULL,
name VARCHAR(50) NOT NULL,
card_text VARCHAR(4000) NOT NULL,
CONSTRAINT PK_Cards PRIMARY KEY CLUSTERED (id)
)
GO
CREATE TABLE dbo.Card_Rulings (
card_id INT NOT NULL,
ruling_number INT NOT NULL,
ruling_text VARCHAR(4000) NOT NULL,
CONSTRAINT PK_Card_Rulings PRIMARY KEY CLUSTERED (card_id, ruling_number)
)
GO
CREATE TABLE dbo.Card_Ruling_Referenced_Cards (
parent_card_id INT NOT NULL,
ruling_number INT NOT NULL,
child_card_id INT NOT NULL,
CONSTRAINT PK_Card_Ruling_Referenced_Cards PRIMARY KEY CLUSTERED (parent_card_id, ruling_number, child_card_id)
)
GO
ALTER TABLE dbo.Card_Rulings
ADD CONSTRAINT FK_CardRulings_Cards FOREIGN KEY (card_id) REFERENCES dbo.Cards(id)
GO
ALTER TABLE dbo.Card_Ruling_Referenced_Cards
ADD CONSTRAINT FK_CardRulingReferencedCards_CardRulings FOREIGN KEY (parent_card_id, ruling_number) REFERENCES dbo.Card_Rulings (card_id, ruling_number)
GO
ALTER TABLE dbo.Card_Ruling_Referenced_Cards
ADD CONSTRAINT FK_CardRulingReferencedCards_Cards FOREIGN KEY (child_card_id) REFERENCES dbo.Cards(id)
GO
To get all card rulings for a card:
SELECT *
FROM dbo.Cards C
INNER JOIN dbo.Card_Rulings CR ON CR.card_id = C.id
WHERE C.id = @card_id
To get all cards referenced in a ruling by a given card:
SELECT C.*
FROM dbo.Card_Rulings CR
INNER JOIN dbo.Card_Ruling_Referenced_Cards CRRC ON CRRC.parent_card_id = CR.card_id
INNER JOIN dbo.Cards C ON C.id = CRRC.child_card_id
WHERE CR.card_id = @card_id
This was all off the top of my head and is not tested, so there might be syntactic errors, etc.
Your front end would be responsible for maintaining the references. This is probably desirable since it avoids the issue of someone forgetting to put quotes around a card name in a ruling text, etc.