Charon Drive

Used almost exclusively by Gor ships, the Charon Drive rides on the river of the dead, traveling through the outer planes to arrive at their destinations.
The Charon Drive has some benefits compared to a FTL drives; When traveling to areas with many recently dead (Such as large battlefields), travel times are proportionally reduced. They are not dependent on Drift beacons and the drives are significantly cheaper in power their competitors.
These benefits, however, most would agree are greatly outpaced by the drawbacks.
The drives require a Ferryman, a specialized spellcaster who knows how to guide the ship down the streams of the Styx and training these takes years of study. If your Ferryman dies while you are on the material plane, you are stuck, giving most Gor ships a single point of failure. If he dies while on the Styx, that is magnitudes worse; you can expect to flow on the river of dead souls for all time.
Additionally, when traveling to places with very few dead, the drives are extremely imprecise, forcing Gor ships to gather at vast distances when mustering their fleets to stop them from accidentally crashing into each other as they leave the Styx. While they are great at reinforcing each other once the battle has been joined, their effectiveness largely relies on either suffering great losses or inflicting them early on.
Lastly, there are the threats of the Outer Planes themselves. All Gor ships are covered in protective seals and runes, to keep out curious fey, raging elementals, or the screaming demons of the abyss. Even then, these protections are not always enough and Gor ships regularly experience attacks on their ships by various Outsiders drawn by the allure of fresh meat. A Gor ship's crew traveling via Charon Drive must always be at battle stations, ready to defend themselves, often leaving them tired and worn out when they come back into Real Space.