Then, your opponent taps six of there ten mana and plays Mindslaver
This is a key difference from English packs, which always include at least one energy card
If you have Leap on the board and Deathrender attached to an elf, sacrificing the elf for one mana with Leap will allow you to place a creature of any size from your hand onto the battlefield for free and equipped with Deathrender, and then it replaces that creature from your hand by revealing cards until you get another creature to hold onto
It is a cost seven, uninkable, card, but any number of characters can be used to sing it for free
In black and green, the options for creature recursion and sacrifice outlets are numerous, so consider Gravecrawler or Reassembling Skeleton, or cards that are already mutants (and believe me, we expect more) and think of them as draw two cards when they die