Hi!
The one where it makes a PQ0 planet/planets with in so many sectors of a given planet where the precurser artifact was recovered would make lets say everything within 2 sectors at least a pq8 or something like that.
I had that event in my beforelast game (DL version), but it was limited to just one system of Arceans, and has improved three class-0 planets to class 4 without terraforming tiles. Not much use for my all-factores approach. I also couldn't gather enough influence from them to flip the arceans' planet in system, because they all had planetary influence 0. I dumped there 6B pop and filled the remaining 3 tiles with markets.
IIRC I've seen that event in only one more game, loooong ago.
BR, Iztok