Echoing Strike

Insight is a good and cheap option for

Echoing Strike to level your character through nightmare and even hell. It has mediatation aura, 35% Faster Cast Rate, 200-260% Enhanced Damage and 1-6 To

Critical Strike. Which is all very useful for

Echoing Strike.

A level 48 Warlock can equip a

Colossus Voulge Insight (non

Eth) by means of level 15

Levitation Mastery and at least 2 points of STR every level up. You can easily level up your Mirror Blades to 20, put 1 point to

Echoing Strike for the synergy, and hit 5K. You don't need anything else other than a

Colossus Voulge Insight to achieve this kind of damage. Add some form of dual leech and you'll clear Nightmare in no time. This DPS can also extend deep into Hell difficulty as well.

Remember that as of the time posting this,

Echoing Strike doesn't scale with attack speed and scales with FCR.

Note that

Echoing Strike applies Deadly Strike,

Critical Strike, and

Levitation Mastery's crit chance. They cannot occur at the same time but it effectively all increases your chance to double damage. It is also note worthy that you can spread the blades wider by casting it closer to the Warlock. The closer the cast location the wider the spread of blades become. The further away, the more concentrated it becomes.

-Freezing Targets does not proc on

Echoing Strike.
-On Striking effects will not proc on

Echoing Strike.
-Elemental damage, Poison damage, and effects such as cold damage and chill effects will still work normally.