Angel's Chalice

When Angel's Chalice enters the battlefield,
choose a color.
{t}: Add two mana of the chosen color to your
mana pool.
Whenever you cast a spell of the chosen color,
you may pay {x} and tap Angel's Chalice. If
you do, search your library for an Angel creature
card with converted mana cost X or less and put
it onto the battlefield. Then shuffle your library.