My proposal for a super structure is a portal generator. Only 1 per player, very expensive to build 1M+ energy + minerals?. Costs energy and G to open and maintain a portal. A portal takes 20000 ticks to open and is visible to all players whilst is opening. Once open the portal can be used by any player in either direction like the portals in SK rooms. Portals last 20K ticks. For a number of reasons players wouldnt be able to open portals between shards.
This would provide a way for players to wage war across much larger distances. Forcing a portal to remain open for a number of ticks prevents hit and run attacks with no option for retaliation.
We could also add functionality to allow the creating player to extend the life of the portal by adding more resources but this shouldnt allow the creating player the ability to close the portal without warning