Here is the full list of all 13 Boomerang Fu achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Dodged a lot of boomerangs
Being on time to things
Telefragged an opponent
One of your "teammates" killed you
Killed many opponents with the telekinesis powerup
Shattered a lot of frozen enemies
Killed a lot of enemies with fire
Killed opponents while unarmed
Killed an opponent after dying
Regularly killed yourself with the explosive boomerang
Mastered the disguise powerup
Squishing several opponents with moving blocks
Spent a lot of time hiding in the bushes