Braum turns your assassin into a tank
Combine his W with the locket of iron solari, and anyone you jump to is getting a decent 40+ magic resist, and 20 something armor. The active will add a shield of 230 points, and then you can shield again for 10% of your max health. Not to mention all of the aggro you've blocked with the intercept from your E ability. Combine this with other champs like Shen or Maokai who add shields or damage reduction onto other champions, and any one player on your team can become incredibly hard to down in team fights.