Roboquest

Here is my configuration that made me unlock this achievement. I was able to get over 1500 damage pretty often with these upgrades and items. You will need to play the elementalist.

CHARACTER UPGRADES:

UPGRADES
- increase comet damage by 15%
- increase critical damage by 20%
WARNING BLAST
- using trinity increases weapons and comet damage by 35% for 6 seconds
- while warning blast is active, increases weapons and comet auto-critical by 20%
CRITICAL BURST
-increases trinity and comet auto-critical chance by 10% and their critical damage by 50%
-Transforms comet into a ray which can apply critical damage with a X1.5 critical ratio
ELEMENTAL RESONANCE
-increases all damage against enemies by 20% for each elemental effect they are affected by
- increases elemental auto-critical chance by 10% and it's critical damage by 10%
METEOR
- using trinity increases your next comet damage by 75% and radius by 50%
-increases comet damage by 30% when hitting a single enemy

ITEMS ( I had more than these but those are the ones that affected the comet damage)

-RAKE: increases all damage by 10% on turrets
-TIN CAN: increases all damage by 20% against stunned and staggered enemies
-CUCUMBER: while you have no scratch damage increases all damage by 15%
-FANCY BUTTON: increases melee and comet damage by 30% against enemies with more than 90% health
remaining

Now that you have these perks and items the trick is to use trinity and, in under 6 seconds after that, use your comet on a SINGLE enemy with his health over 90% in his weak point and preferably while you have no scratch damages. You may need a couple attempts because of the RNG but it is pretty easy to get.

Here is my configuration that made me unlock this achievement. I was able to get over 1500 damage pretty often with these upgrades and items. You will need to play the elementalist.

CHARACTER UPGRADES:

UPGRADES
- increase comet damage by 15%
- increase critical damage by 20%
WARNING BLAST
- using trinity increases weapons and comet damage by 35% for 6 seconds
- while warning blast is active, increases weapons and comet auto-critical by 20%
CRITICAL BURST
-increases trinity and comet auto-critical chance by 10% and their critical damage by 50%
-Transforms comet into a ray which can apply critical damage with a X1.5 critical ratio
ELEMENTAL RESONANCE
-increases all damage against enemies by 20% for each elemental effect they are affected by
- increases elemental auto-critical chance by 10% and it's critical damage by 10%
METEOR
- using trinity increases your next comet damage by 75% and radius by 50%
-increases comet damage by 30% when hitting a single enemy

ITEMS ( I had more than these but those are the ones that affected the comet damage)

-RAKE: increases all damage by 10% on turrets
-TIN CAN: increases all damage by 20% against stunned and staggered enemies
-CUCUMBER: while you have no scratch damage increases all damage by 15%
-FANCY BUTTON: increases melee and comet damage by 30% against enemies with more than 90% health
remaining

Now that you have these perks and items the trick is to use trinity and, in under 6 seconds after that, use your comet on a SINGLE enemy with his health over 90% in his weak point and preferably while you have no scratch damages. You may need a couple attempts because of the RNG but it is pretty easy to get.