Database: card_games
Question: Among the cards with converted mana cost higher than 5 in the set Coldsnap, how many of them have unknown power?
SQL: SELECT SUM(CASE WHEN T1.power LIKE '*' OR T1.power IS NULL THEN 1 ELSE 0 END) FROM cards AS T1 INNER JOIN sets AS T2 ON T2.code = T1.setCode WHERE T2.name = 'Coldsnap' AND T1.convertedManaCost > 5