Wildcard nodes are like Player node, except instead of matching only specific intents, they always match. They're useful for catching anything else a player might say.
By default, if there's no route from the current Character node to a directly-connected matching Player node, Charisma will additionally search through every subplot for a matching Player node before considering wildcards.
Allow subplots is toggled off, then instead Charisma will not search subplots and prefer the wildcard route. This is useful if you're in the middle of some critical dialogue that you don't want the player to drop out of.
If character improvisation is enabled for your story, you will also see an
Allow improvisation checkbox. Leaving this on will allow your character to generate a response to be sent to the player before the next Character node. See the character improvisation docs for more information.