Name:Night
ManaCost:B
AlternateMode: Split
Types:Instant
A:SP$ Pump | Cost$ B | ValidTgts$ Creature | TgtPrompt$ Select target creature | NumAtt$ -1 | NumDef$ -1 | IsCurse$ True | SpellDescription$ Target creature gets -1/-1 until end of turn.
SVar:Picture:http://www.wizards.com/global/images/magic/general/night_day.jpg
Oracle:Target creature gets -1/-1 until end of turn.

ALTERNATE

Name:Day
ManaCost:2 W
Types:Instant
A:SP$ PumpAll | Cost$ 2 W | ValidTgts$ Player | TgtPrompt$ Select target player | ValidCards$ Creature | NumAtt$ +1 | NumDef$ +1 | SpellDescription$ Creatures target player controls get +1/+1 until end of turn.
Oracle:Creatures target player controls get +1/+1 until end of turn.