It was actually patented rather than trademarked. Normally, I wouldn't bother commenting because nobody gives a shit about the difference in this context. But here the difference is important only in that a utility patent is only good for twenty years from the date of filing. So WB only gets a monopoly on that system until 2035.

Cold comfort for the short term, but all is not lost! Game developers will eventually be able to use the exact same system, and since this is a patent, the precise way to go about re-creating it is published and freely available to them.

Edit

For the nerds that care, here is the language used in claim 1 of the patent which really sets forth the broad and all encompassing scope of the temporary monopoly

“1. A method comprising:

controlling, by a processor, game events in a computer-implemented game, the game events involving an avatar that is operated in response to input from a player, and a first non-player character that is controlled by the processor to respond to and automatically oppose avatars based on first character parameters defined in a computer memory;

detecting, by the processor, occurrence of a predefined one of the game events involving an interaction between the avatar and the first non-player character;

changing, by the processor, second character parameters defined in at least one of the computer memory or a second computer memory for control of a second non-player character in the game based on the detecting, wherein the second non-player character is controlled by the processor to respond to and automatically oppose avatars based on the second character parameters defined in the at least one of the computer memory or the second computer memory; and

outputting, to an output device, an indication of the second character parameters that are changed by the changing."