Sunken Selarion

Selarion Drowned comes into play tapped.
{t}: Add {u}.
While Selarion Drowned is in play, Merfolk
creatures cost out {1} less to play.
Elves on the battlefield gain the Merfolk type
and blue color.
"Selarion's subsidence into the sea was not at all a
tragedy. And act of elvish spell and will. More a
quiet sigh than a scream so shrill."