Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact
you control.
When Emry, Lurker of the Loch enters the
battlefield, put the top four cards of your
library into your graveyard.
{t}: Choose target artifact card in your
graveyard. You may cast that card this turn.
(You still pay its costs. Timing rules still
apply.)