Good grief! That's some seriously huge firepower
_300_ Spire Frigates? I don't think anything in the game can come close to withstanding that kind of firepower.
Yea, the motherships are lethal to spire capital fleets from long range, but are vulnerable to wormhole ambushes where they don't have that range.
One thing I discovered with the motherships is that there's basically an upper-limit to how much damage any one unit can take with health values that fit in an Int32. I could stack a lot of forcefield modules on it but that can only be taken so far. Also gave it massive armor but even 20% of a DNs firepower is murder.