Emry, Lurker of the Loch

You must follow the normal timing permissions and restrictions for the target artifact card. Unless it has flash, you'll most likely only be able to cast it during your main phase while the stack is empty.

The cost reduction ability reduces only the generic mana in Emry's cost. The colored mana must still be paid.

You'll still pay all costs for a spell cast this way, including additional costs. You may also pay alternative costs if any are available.