Once celestial champion is in its 3rd phase, the lasers will cause insane lag spikes ( both for host and client ). This is due to the mechanic that the laser repositions every item on the ground when it hits them.
If there are lots of lets say, moon shards or rocks on the ground, and the laser hits them, it results in ALL of them being repositioned and hence sending huge package data to client. Today we were doing this in the middle of a frog rain, and the lasers were moving the massive stacks of frog legs on the ground and the game was almost freezing for a few seconds each time this happened.
To notice the impact better, try spawning 1000 moon shard or rock under yourself ( or anywhere that laser hits ) and then let the champion use its laser. You will notice the lag, specially on a dedicated server and when you are not the host.