I have a lunchtime board game group that loves Avalon, so we play practically ever day. After more than a year of play, we ended up adding more and more "house rules" in, to keep things exciting and fresh.
I thought I'd share our modifications here, even though they probably would only work with a very regular crew.
Obviously, we always play with the core 4 bad guys.
Mordred, Morgana, Oberon, and Assassin. No changes here.
Merlin and Percival are in and also have their normal rules.
Then we wanted to get rid of boring "vanilla" characters, who have no name or special power, without unbalancing the teams if possible.
So, we changed two of the nameless good guys into Guinevere and Arthur.
At the end of the narration phase, these two Lovers both open their eyes and see each other - similar to Masons in One Night Ultimate Werewolf. You'd think that these two would make the good guys too powerful, but often they are too obvious and this exposes Merlin. Fun balance.
Then to balance this out, we turn another good guy into Galahad.
If you're playing with Lady of the Lake, Galahad is a regular good guy - EXCEPT, when tested by the Lady, he must show Red. This hurts the reliablity of the Lady in a fun way, as now you have an additional level of lying about what people see from the Lady.
Because our group plays so much, we eventually add the Trapper module from regular resistance, and dropped the Lady of the Lake. Then we gave Galahad a new special rule - if Galahad is Trapped, after the Trapper sees Galahad's card, but before the cards are shuffled together, Galahad can flip over his Galahad card and then steal the trapping power, and trap somebody else instead.
For our tenth character, we use the Puck idea from here:
Which we found to be very fun, as he prevents things from being too easy for both teams.
For bonus zaniness, we occasionally will add one final crazy rule: the Galahad player is not allowed to speak. If he accidentally speaks, he must flip his Galahad card before the next mission result, or Merlin is assassinated automatically.
To counter this new weakness, Galahad gains an extra power, in addition to his "steal the trap" power. If Galahad is ever Approved as a team leader, he can reveal his Galahad card before the chalices are handed out - this mission automatically succeeds, even if it's mission 5. After Galahad uses either power, he can speak as normal.
We find that this leads to hilarious scenarios where 10 people all play via pantomime at first, until 8 and then 4 and then 2 people are claiming Galahad by the end.
Anyway, hope that some of these ideas are interesting or helpful to anybody that plays this game hundreds of times, like us!
Then to balance this out, we turn another good guy into Galahad. If you're playing with Lady of the Lake, Galahad is a regular good guy - EXCEPT, when tested by the Lady, he must show Red. This hurts the reliablity of the Lady in a fun way, as now you have an additional level of lying about what people see from the Lady.
Ooooohhh, I like this. I have been ambivalent about Lady Of The Lake because it is sooo hard to lie your way out of a LOTL exposure. This makes it easier.