Could be a GM thing too. Had one cast a cat illusion on my pet and when I zoned it was my dog again but it was the size of that bazu
I think there was a bug where jester could randomly grow people and sometimes they would be super sized.
I think there is a trick and its not random. Saw 2 ice giants way bigger than normal sized and then later that day a tiger that was even bigger. Had to lev up to top of bank to get him in a screenshot.
There is a trick. It's not random. I never got the hang of it. Can do it to the aspect of the brood, ice giant etc.