It wasn't just the pillar.
The entire hall, well, the walls of the hall, had been neatly cut through as well. The defensive array placed here was enough to allow even peak Tier IV combatants to fight without having to worry too much about destroying the entire place, but when a being whose strength surpasses Tier IV attacks with full strength, even the array was unable to withstand it.
The entire floor started rumbling as the ceiling started falling down. The immense storm of mana made cracks appear before the ceiling broke into pieces and crashed down, forcing everybody to stop fighting in order to dodge the debris and not get crushed.
The floor cracked as well thanks to the debris, and soon, some parts of the floor caved in before being crushed, turning the once spacious hall into one filled with cement and steel armature that had been used to build the ceiling.