Blackwing - Decay the Ill Wind

Once per turn, during the End Phase, if this card is in the Graveyard because it was sent there this turn: Take 1000 damage. When this card is Normal or Special Summoned: You can target 1 "Blackwing" monster you control, then activate 1 of these effects;
• Increase its Level by 1.
• Reduce its Level by 1.
You can only use this effect of "Blackwing - Decay the Ill Wind" once per turn.