How do I get the "Massive Blow" achievement?

What's the most reliable way to achieve "Massive Blow"?

Solution 1:

This can be easily achieved in the cathedral, with the wizard.

After you get to level 10+ go around the cathedral (whichever level) and gather up a few monsters.

After that, use frost nova to stun them and deal some damage, and then use wave of force to kill them all with one blast.

This is the way i did it and everything went incredibly smoothly.

Hope i could help, cheers :)

Solution 2:

Another option is to find the Jar of Souls event and wait for lots of things to spawn.

Then:

• As a Witch Doctor, try using Grasp of the Dead.
• As a Barbarian, try using Hammer of the Ancients.
• As a Monk, try Crippling Wave.
• As a Demon Hunter, try using Rapid Fire.
• As a Wizard, the Frost Nova + Wave of Force combo.

Solution 3:

Got it by accident using Disintegrating Ray on the mobs at the very start of Act 4. There's a billion of them and they have no life. Wait till then imo.