Gavin Guile, the Prism

Gavin Guile, the Prism is all colors and has
hexproof from colored spells.
Colored spells you cast cost {1} less to cast for
each other colored spell you've cast this turn.
You may pay mana as though it were mana of
any color to cast colored spells.
The Prism alone may split light from within
his very body.