The Xekian Mothership

Xekian Mothership enters the battlefield tapped
When Xekian Mothership enters the battlefield,
place 2 1/1 Xekian creature tokens onto the battlefield.
When Xekian Mothership is tapped, place two
energy counters onto the battlefield, these may be sacrificed at any time to place +1/+1 counters on target creature you control for each token sacrificed