This deck is for the Gym Buddies achievement: Use Bulk Up to create a 4th copy of the same minion. The wording here seems confusing, but all you need is two of the same minion in hand and Bulk Up. Just draw and play Bulk up when you have a Sword Eater in hand. Play the second one on the second Sword Eater. Just make sure not to waste the spell too soon. The rest of the deck is just draw and sustain.
The achievement works a bit weird. I got it the second time I played this deck when I made the first copy of the taunt minion. In the first match I made 3 copies. Maybe it counts all copies over multiple matches? It shouldn't but it seems that way. I also beat a secret paladin in my second match. So that was cool. Paladin's can't deal with HUGE taunts.
Good luck with the achievement.