Half Horse... Half Reloaded?? — Do Boosters Influence Expansions?

[Really Impressive Title]

So after purchasing and taking inventory of “Half Horse, Will Travel”, I noticed that it comes with 9 uneven amounts of race/class enhancer cards: 6 class (Legend & Elite) and 3 race (Elder).

I also happen to have a copy of “Reloaded!” that I have not yet integrated into my play deck. But I noticed that THAT set comes with 9 race/class enhancers as well: 3 class (Master) and 6 race (Dark & High).

Which means combining these two sets results in an even 18 cards, 9 cards of each, to perfectly balance out both types of enhancers. I think this is both fascinating and a bit baffling knowing that “Reloaded!” (or “Game Changers”) is not considered a main expansion. That is to say, they are not part of the core Munchkin experience defined by the coveted numeral naming system.

Call me a Thanos but I like my Munchkin deck to be as balanced as possible. I actually enjoy analyzing the game, keeping track of card types and trying to make the experience as diverse and “fair” as it can get (with respect to the spirit of Munchkin). Which is why I’m so intrigued by this “Half Horse/Reloaded” combo situation. It seems obvious that these two sets intentionally compliment each other. That could not have been an accident. So, was this on purpose? And what other booster sets and mini expansions have had a direct influence on the main (i.e. numbered) fantasy expansions?