Since last time, we admittedly suffered from sub-optimal engagement decisions by the SDV, we’ll now be looking at a more reasonable scenario.
Now, the same officer-in-training who had failed the previous scenario is allowed a repetition. This time, he decides to try another approach: He’s taking the Oberth to a highly-eccentric orbit, timed to reach apogee just as the AKVs get close. This minimizes the relative engagement velocity.
The AKVs still spend ten km/s. Their original plan was to be able to decelerate again - but as the Oberth comes out to meet them they accelerate to a relative velocity of twenty km/s instead. Suicide, but they are expendable after all.
As the Oberth reaches apogee, the AKVs come into range. Range for the 100 MJ lasers is 2250km, or 7500km at half-damage. Half-damage still requires targeting armour weakspots to do any damage. At 7500km, that means rolling against 1 - clearly impossible. Not targeting weakpoints, they will roll against 14 at 2250km out.
Turn 1 AKVs are 2250km out. Two lasers are dodged, the others hit. Aggressive Armadillo takes a total of 21 damage. An armour system and the EM gun are disabled. She also fires her railgun at them - it will hit during turn seven. The three AKVs left begin firing their EM gun. Not to destroy the Oberth right now, but to force her to manoeuvre. Those will hit in 105 instead of 113 seconds. The Oberth can change trajectory by one ten-mile hex per three turns. It now begins to do so.
Turn 2 AKVs are 1850km out. All lasers hit. Brave Beaver takes 37 damage, disabling three armour systems and the gun. Another railgun round is scheduled to hit at turn seven. The AKVs fire another two shots, which will also arrive at turn six.
Turn 3 AKVs are 1450km out. Three lasers hit, doing a total of 22 damage, disabling three armour systems. A third shot is scheduled to arrive during turn seven. The AKVs add another two railgun rounds.
Turn 4 AKVs are 1050km out. All lasers hit. Curious Crow takes 22 damage, and four armour systems are disabled. It also adds yet another kinetic round. At that distance, the 10MJ lasers now also come into play. They roll against 8 to hit weak spots in armour. However, they all miss. The AKVs add two railgun rounds - and while the Oberth will be able to avoid the previously fired rounds, these cannot be evaded anymore.
Turn 5 AKVs are now 650km out. All four lasers hit, this time Dangerous Dalmatian, for 36 damage, disabling four armour systems. Another railgun round - and the AKVs are now unable to change trajectory far enough to avoid that and each subsequent round. The rapid-fire lasers hit Dangerous Dalmatian and Brave Beaver, each with two shots. Brave Beaver takes another 17 damage, bringing it to -24HP, and disabling even more systems. Dangerous Dalmatian takes 18 damage, disabling the EM gun and bringing it down to -26 HP - still not enough to actually kill it. The first AKV adds another kinetic round, and all manoeuvre for collision.
Turn 6 AKVs are now just 250km out. This is pretty much the time to panic for the Oberth: Three railgun rounds will impact next turn unless dodged, and the AKVs are hard behind them. Desperate, each 100MJ laser now targets the weakpoints of each AKV. Luckily, all manage to hit. Aggressive Armadillo, the most intact AKV, takes 24 damage, bringing it to -15. Brave Beaver and Dangerous Dalmatian are actually destroyed, failing their HT rolls.
Turn 7 Now, here’s the showdown. In the same turn, the AKVs and the Oberth are intercepted by the kinetic strikes. But, first, the lasers. Two strikes on each of the AKVs. All of them hit. Aggressive Armadillo is hit for another 39 damage, Curious Crow for 62. Both fail their HT rolls. The kinetic strikes on the AKVs are now unimportant, but the ones on the Herman Oberth are still very much relevant. They roll against 9 to hit - and two actually do make it. Damage is 234d per, reduced to 210d due to armour. The first one does 734 damage. It brings the Oberth to -634HP, enough to destroy it at once. The second one is sufficient to get reduce it to vapour.
Summary From a tactical point of view, the attackers just invested $60M of AKVs to destroy $207M of SDV. That’s probably a good trade-off, and shows their vulnerability. Using more AKVs would have resulted in fewer casualties, as would a higher initial velocity.
From a game perspective, there are a few weaknesses to consider. First of all, turns took quite a bit of time to play out, and tracking armour damage seems to add complexity.
Damage seems acceptable: Kinetics present a significant danger, but are restricted due to flight time. Particle beams would have neutralized the AKVs, probably in time to avoid the kinetics.
Edit: Afterwards, I did notice that the Oberth mounts UV lasers, not lasers. They have a longer range at 4500/15000km. This probably would have sufficed for the Oberth to survive.