It's been a while, but IIRC, you need at least one constructor for each level of development and 10 turns to activate. Noctilucus is right, it only goes one parsec/turn and destroys stars, not planets. Of course, the supernova'd star takes out the planets and the old asteroid fields, turning what used to be planets into asteroid fields. I don't know what it does to fleets, since I never attacked anyone with the one I built.    I just used mine to make asteroid fields and clean the map a little. I assume it blows up the enemy and I think I remember a journal entry or something that your fleets make a run for it. I can report that somehow the Terror Star doesn't blow itself up, so you can use it again if your enemies don't get it first. It does look cool.

I'm just surprised that the U.P. hasn't outlawed sneak attacks yet. In my games that almost always happens in the first three years.   

A couple more points:



I have never attempted this, but the AI won't allow you to build influence starbases in it's space, not even an ally, so I doubt it will allow you to build a terror star either. Could someone please post back and confirm or deny this for me? My advise, from what I believe to be true is to build them just outside of your target's area of influence, and move them into position after.



They *attempt* to make a run for it. If your fleet has enough movement points left to completely clear the area of effect, then they will survive. (Learned this one the hard way). So you won't necessarily be able to move into position and attack on the same turn. Wait a turn for their movement points to refresh, or better yet, move them away yourself before attacking.

Terror stars are neat gadgets, but they are too expensive, slow, and completely helpless to be game-changing. They are really just for mopping up at the end of a game. The effect is impressive, but once I made and used one I got the 'been there, done that', and haven't made another since.

Influence SB's can be built in the AI's territory (it is only 1 negative factor in the diplomacy) but I've read on this forum that the AI will automatically attack any terror stars within its territory. Which would make sense

They are more of a Fun factor than anything else. You definitely have to build at least one, just to blow the snot out of an entire star system. I Nuked the Altarian Refuge Home world with mine. But they are DEAD slow and the other AI's will attack them if they are being built in their space.

Oh, and expect, if you use more than one, that the AI will probably surrender.