Proud writer for iSlayTheDragon
So, does this feature improve the 2 player game, a lot?
The real question.
For a 2 player game, is that duality enough to justify buying this?
I consider these dice (black and orange) to add interesting decisions to the dice assignment and consider it an improvement to the game. I wouldn't say it improve the game a lot and not specifically to the 2-player game.
The main reason is that you are only guaranteed one die with this power (black die) and may not gain any others (orange dice). This is similar to how reassignment works, you have the Dictate power by default and may receive others through developments (or may not). However, orange dice are more scarce than reassign developments so it's less impactful on the game as a result.
These new dice are definitely cool and add something to the game but I wouldn't buy the expansion hoping that specific feature will drastically improve the 2-player experience. On that note, I do think this expansion is well worth getting if you enjoy the base game.