I suggested the "transforms over time" idea a while back, and it got shouted down rather forcefully
Seems strange that it would, because creatures already get elderly over time, so why shouldn't one get better? Say, for instance, if you took the scales that make creatures start older/get older, faster, you might use this as an advantage for Aboleths, since you would be able to recruit regular Aboleths that would eventually transform into Mind Lords.
Ofcourse, they're an extreme example, since they've got lifespans in the tens of thousands of years, but what if there were some in-game effects that rapidly aged creatures? Say a spell or a special site. Something that was negative for most Nations, but that could be taken advantage of by a few.
And I like your egg idea. It's not the first time I've heard it, but I like the (I think new) idea that it would hatch into various different critters. I'd apply it to my Dragons, (lesser versions, ofcourse, that could get older over time) and stick it in as a high level Summons, with the chance that you'd just end up with a Drake/Wyvern/Couatl/Salamander, etc. Dud version would be a lizardman or a kobold
