The Mtenda Lion is a solid card for any green deck, especially a green "weenie" deck: it comes out early and hits hard. If you're playing green, your opponent needs to be ready to handle your big creatures by turn 4 or 5. Even if she can produce to prevent the Lion's damage, doing so often slows down her deck development too much. If your opponent can handle the Mtenda Lion, she's playing heavy blue. Have some blue hosers in your sideboard to swap in for your Mtenda Lions.