During the climactic confrontation at the end of Betrayer of Worlds:
Achilles' attacks Kl'mo with a pair of relativistic planet-busters. Such weapons are difficult to defend against because 1) they travel close to the speed of light, and 2) they release enormous amounts of energy upon impact, thanks to their speed.
With hyperdrive, one could catch up to the missiles and "hyperdrive them away". But Ol't'ro solve this problem after the missiles enter gravitational singularity of the system, where hyperdrive no longer works.
We are told that Achilles saw a bright flash when the missiles were "taken care of", and then a fast moving object showed up close to his ship.
How did Ol't'ro handle this attack? Did they figure out that hyperdrive does work inside of gravitation wells, just like Tunesmith realized in Ringworld's Children?