Davnor, Pact Breaker

Partner with Rob, Pact Seeker.
Davnor, Pact Breaker costs {x} less to cast where
X is the number of ritual counters on Rob,
Pact Seeker.
When Davnor, Pact Breaker Enters the battlefield
each playersacrifices all non legendary non-land
permanents. Then search your library for a card
and put it in your hand.