https://www.ddo.com/forums/showthread.php/497600-Strahd-Circlessomeone posted that lotro had the same issue where the circle icons displayed are false and the real area of effect radius is a square, not the circle.
I tested cleaves around 3 years ago or so and learned that they behaved the same way, but never thought about it until i read that post. I posted my findings here in a thread discussing weapon ranges with ffs, though good luck finding it through my thousands of shit posts.
You can test for yourself. So far I just tested both death auras and negative energy burst. And they are actually squared.
If someone could test haste/rage/buffs etc. You would need a person to be the dummy there. I will test the dps spells on the next lama ( fireball, ice storm, energy burst, etc ). Or if i can get a person to sit there. fireball, hellball and ice storm can be cast at your feet to test this.
To clarify, stand with your character facing the dummy. Test until you are put out of range when using cleaves/spells. Then simply imagine a X axis from your character's center. Now turn to the sides where the points of the square would reach ( squaring your left/right arms to the dummy ). The hits/spells should land and trigger the dummy.
screenshots;
directly facing and cannot hit.

same exact spot, but facing to side and arms squared with target = hit

same exact spot, but facing backwards and to the side with arms squared to target = hit

so, yeah, if anyone could be bothered to alert the devs and tell them theyre retarded for using circles, and that theyre ignorant of their very own game that they own.