Topologic Gumblar Dragon

Flying, Trample, Menace
You may sacrifice any number of creatures, reduce this card’s cost by X where X is the number of sacrificed creatures.
When this creature enters, sacrifice any number of creatures and/or discard any number of cards. Your opponent must then:
•Discard X cards
•Sacrifice X nonland permanents
Where X is equal to the total number of cards discarded and sacrificed.