Sliver Duplicator

You may sacrifice a sliver you control in play to
have Sliver Duplicator cost {2} less to cast.
Slivers you control have Undying.
When Sliver Duplicator enters the battlefield,
create a 1/1 colorless sliver creature token.
When Sliver Duplicator leaves the battlefield,
create a 1/1 colorless sliver creature token.