Step 1) Navigate the menus until you find custom challenges.

Step 2) Select custom challenges.

Step 3) Chose Blind Justice as your level (its the first and easiest).

Step 4) Activate the takedown projectiles perk (this perk enables
you to use quick fire batarangs to immediately takedown enemies).

Step 5) Back away from enemies so they don't hit you then quick fire
batarangs for all levels.

Step 6) Win!