Seed of Corruption was way overpowered on the PTRs and Blizzard have now fixed it, but lumped the cost on Warlocks.

In "fixing" the Seed of Corruption issue that players discovered almost immediately after the PTRs came back online today, Blizzard decided it was best to blank all Warlock talents and abilities and require the class as a whole to re-train every single spell from scratch. The total cost? 350g. And that doesn't even take into account our pets, which were also wiped from our spell books and must be reacquired via their original quest lines - an unfortunate and unfair result to a problem Blizzard created.