Batwing Brume
Instant
Prevent all combat damage that would be dealt this turn if 
was spent to cast this spell. Each player loses 1 life for each attacking creature they control if 
was spent to cast this spell. (Do both if was spent.)
Richard Kane Ferguson
The List (PLST)
• #EVE-81Rulings
The spell cares about what mana was spent to pay its total cost, not just what mana was spent to pay the hybrid part of its cost.
(wotc • 2008-08-01)
The spell checks on resolution to see if any mana of the stated colors was spent to pay its cost. If so, it doesn’t matter how much mana of that color was spent.
(wotc • 2008-08-01)
If the spell is copied, the copy will never have had mana of the stated color paid for it, no matter what colors were spent on the original spell.
(wotc • 2008-08-01)
Rulings
The spell cares about what mana was spent to pay its total cost, not just what mana was spent to pay the hybrid part of its cost.
(wotc • 2008-08-01)
The spell checks on resolution to see if any mana of the stated colors was spent to pay its cost. If so, it doesn’t matter how much mana of that color was spent.
(wotc • 2008-08-01)
If the spell is copied, the copy will never have had mana of the stated color paid for it, no matter what colors were spent on the original spell.
(wotc • 2008-08-01)