It was an normal AI AuroraAlpha.
And I think 3-4 is the highest number of Beam cannons. Well I could add 8 to one Obelisk but don't think the range increased more after 3-4.

Even if the radious shows more, you still can't shoot all the way to the edge.
I think the range is the same as Juggernauts.
My battle field was covered of about 8-10 destroyed Juggernauts. I captured them with Saboteurs and then attacked him. Launched a nuke and finished him of with the Juggernauts :P
By the way, a good tactik is to use the Cloaking Ability (which cost 1500 and has the NOD symbol on it). I camouflaged my Juggernauts and Avatars, did some surprice attacks to the AI :)
Ow, by the way, took a picture just before the Nuke explodes, it has an cool effect.

EDIT:
WOW, that's over 16.000 worth of money I destroyed with that nuke!
5 Juggernauts
2 War Factories
1 Armoury
1 Barracks
Edited by user Saturday, March 3, 2007 7:52:22 AM(UTC)
| Reason: Not specified