Currently I'm thinking something like this:
1) Make the spawns happen at a fixed interval (every 5 seconds, or 10 seconds, probably), but adjust the spawn size math so that the numbers are the same as they are now (5 ships/second on diff 10, 2 ships/second on diff 9, etc)
2) Have the game track the total amount of k that's been raided (not gained total, just gained through raiding) and multiply the size of each spawn by (amount_raided/3000). Minimum multiplier of 1.0, though maybe 0.5 would encourage a single light k-raid in each game for variety's sake, dunno.
3) Instead of just always dumping the spawn on the local command station, make a d100 roll on the Wild Mage Table
1-25 spawn normally
26-50 pick a neighboring planet with an AI command station as the spawn point and reroll on this table. If no neighbors have AI command stations, just reroll, allowing for isolated planets being easier to k-raid. Note that multiple roll/rerolls hitting this range for a single spawn could move it more than one planet away.
51-55 pick a random planet in the galaxy with an AI command station as the spawn point and reroll on this table. So even complete isolation doesn't guaruntee "crowd control".
56-65 multiply spawn size by 1.5, reroll
66-70 multiply spawn size by 2.0, reroll
71-75 multiply spawn size by 0.1, and make spawn be composed entirely of zombie guardians (if those are normally seedable in the game), spawn
76-80 multiply spawn size by 0.1, and make spawn be composed entirely of raid starships (if those are normally seedable in the game), spawn
81-99 dunno, but I'll think of something to break this range up into
100 set a flag that makes the game immediately repeat the spawn process after done with this one, reroll
As a sanity-check, if it gets a "reroll" result and has already rolled 3 times, it treats it as a 1 and spawns normally with whatever modifiers are there. Probably increase the roll-limit by 1 per 1000 knowledge already raided or something like that (rather, max_rolls = max(knowledge_raided/1000,3) ).
Anyway, kind of a loony idea, but it wouldn't be that hard to implement so I figured I'd see what y'all think of it