Unexpected death on T3 Avarice

I died at T3 Avarice yesterday evening from the circles on the ground.

Normally they spawn in a wide range around the boss, then they are easy to evade.
This time they took the form of a flower: one ring in the center where Avarice stood and all the other circles in a tight circle around them, slightly overlapping each other.
I was close to the boss, so in a split second I had to decide where to go. I wasn’t sure I was able to completly get out of the pattern so I decided to stay. That cost me my character.

The problem with this specific tight flower pattern is that it creates a lot of areas where two or three circles overlap (inner circle with two outer circles). I must have stood on an overlapping area, since the earlier circles in the game did almost nothing to me.

I had 15K health and Doombringer with a greater affix on damage reduction (26%) and Stone of Vehemen (15% damage reduction). Because of this damage reduction I normally have time to press a healthpot.

The reason this specific pattern appeared was probably because I was the only player at melee range. There was just one other player in the area, but he was most of the time avoiding the fight.

Im not bittered cause I lost my character, but it just felt very unexpected.