The Pale Lady, Moon's Dreamer

Invincible
When The Pale Lady, Moons Dreamer enters the field it becomes Night, and cannot become day as long as The Pale Lady, Moons Dreamer remains in play.
{t}{w}: Place a Sleep Counter on target creature you control. While a creature has a Sleep Counter, it cannot untap.
{ut}{x}{w}: Remove a Sleep Counter from target creature you control, it gains +X/+X

"I like to visit The Lady on the Moon, I help her sleep when I go there!" -Shelby, Adventurous Sheep