Attack for 20 seconds with no counterattacks in an Unranked or Ranked game.
Kill the Brutalisk with lava in "The Devil’s Playground” mission on Normal difficulty.
Kill a Stank before it kills anything on Hard difficulty.
Mutate a Lair during the first 285 seconds of a Melee game.
Have 21 Zerg units morphing simultaneously in an Unranked or Ranked game.