What does level message "Suddenly a rolling thunder erupts !" mean ?

[The Real J.]

Title says it all. I have seen this message every now and then and am curious as to what it implies. At one stage I was farming BDC when I saw it and assumed it was a blue dragon finding BD corpse out of sight and getting enraged but recently I got it in ID and I am pretty sure there were no blue dragons around. Perhaps a lightning vortex spawned ?

[sirtheta]

It is a juggernaut using its charge ability -- https://www.adom.de/forums/project.php?issueid=6467