Battle.net

Kill 15 enemy units with a single Nuke in an Unranked or Ranked game.

Destroy 40 units with a single unit in an Unranked or Ranked game.

Score the rank of Gold in all the challenge missions.

Kill 50 supply worth of units within 15 seconds in a Melee game.

Win 5 1v1 Unranked or Ranked games in a row.