Welcome to the game and forum. Hope you enjoy it.
You just need to do the 7 damage, the Mastermind card at the top is just there for reference telling you what his Master Strike effect is and how much the damage is on each tactic etc.
You can defeat the Mastermind card as well as a 5th tactic if you opt to do the final blow variant but other than that its just a reference guide.
You may also want to check out the awesome FAQ put together by Jacovis found here: http://boardgamegeek.com/filepage/92138/unofficial-collected...