Heart of the Swarm Campaign: Kaldir Achievements- Harvest of Screams

Normal Difficulty:

Harvest of Screams (10): Complete the Mission

Ice Breaker (10): Destroy 20 unfrozen enemy structures during the mission.  This is a bit of a challenge, as the Protoss here are rather dangerous when not frozen.  The key is moving your forces into a base and then destroying pylons and units while leaving structures relatively intact, which can take a bit more micromanagement than some are ready for.

Storm Chaser (10): Complete the mission in 15 minutes or less on Normal difficulty.  Probably the most difficult of the achievements, since you really can't accomplish this without skipping some of the Protoss emplacements or sort of bypassing the bases.  Not impossible- the flash freezes mean you can, if you like, move units in, rip up the towers, and then flee- but this is not the easiest strategy to enact while under repeated timers, and will often require using high-speed zerglings and sacrificing them by not having them flee once they start attacking the spires.

Hard Difficulty:

Psi-lence is Golden (10): Complete all objectives within 12 minutes.  This is a bit of a stretch again, and as with Storm Chaser and Ice Breaker requires very careful attack targeting.  If roaches had their burrowing speed during this mission it would be trivial, but they simply don't, so this becomes a much more severe challenge.  Be aware that 'all objectives' includes the optional one for the Ursadon Matriarchs, so don't try to skip those- you'll lose out on the achievement.