To get the trophy that's called "Phased and Confused", you have to use Maya's special ability, Phaselock, on at least one-hundred enemies. The good news is that it doesn't have to be used on different enemies, just on one enemy 100 times! Very simple trophy to earn if you follow the instructions below!
First off, if you haven't done already or are playing the game for the very first time, chose Maya, the Siren, as your new character and start up a playthrough.
Next, get to level 5 by completing missions and destroying monsters. By the time you gain the mission "Symbosis", you should be at least level 5 or higher. Next, go into your skill tree menu and unlock the special skill, Phaselock.
Once that's done, go to Southern Shelf bay and keep going further until you see a couple of bullymongs. Grab their attention by shooting at them and make sure they are following you. Make your way back to the Ammo Dump and stand next to it. At least two or three bullymongs will stand at a distance and throw rocks at you, hitting the stalactites if you are positioned on higher ground.
Finally, it's really just a matter of hitting
on your Playstation 4 controller to Phaselock one of those bullywongs, then waiting for it to be recharged. Rinse, wash, repeat until the trophy is unlocked.
Have fun, good luck, and happy hunting!