Mass Effect Legendary Edition

To get this you need to destroy the barriers of 25 enemies using the Warp ability. Basically you (or a squadmate) needs to cast Warp on a enemy with barriers (purple bar over their health indicator) and successfully destroy the barriers (deplete that bar) - it does not count if you merely damage the barriers but do not fully deplete them. On easier difficulties a Warp will destroy most enemy barrier defences in one hit, but if you're playing on Insanity you will want to whittle the barriers down to about 25% through other means before casting Warp.

You don't need to do it with your own character, you can direct a squadmate to do it - in this case the easiest squadmate to use is Miranda, as she has Warp and is available from the start. Other characters who can learn Warp are Thane and Liara (Jack's Warp AMMO power does not count). Shepard can learn Warp if they are made an Adept or a Sentinel.

The enemies that most often have barriers are enemy Vanguards - either Eclipse or Blue Suns mercenaries, or Collector troops on higher difficulties (Hardcore and Insanity).

There are more than enough enemies with Barriers throughout the game so that you don't have to resort to any workarounds, but if for some reason you don't want to keep bringing along a squadmate with Warp, you can also find a group of enemies that have Barriers (e.g. the Collectors the first time you encounter them, if playing on higher difficulties), destroy the barriers using Warp, reload the save, and repeat until you have 25.

Went back and tried Necromancer2k8's old solution, and still works like a charm:

Archangel mission, lowest difficulty, use adept as Shepard with Miranda, both lvl 3 warp.
Right after closing those 3 doors in basement you will encounter Blood Pack leader Garn, double shot him with warps, load autosave, rinse and repeat.
I bought Blood Dragon Armor for +15% power dmg.