Banshees can actually cross mountain ash barrier and are immune to many of the supernatural bites and venoms that harm other creatures.
That alone makes them pretty durable. Banshees also have one ability that ranks them higher: their scream.
Lydia Martin initially uses her scream simply as a warning mechanism, but it can also be used offensively.
The scream can be directed to actually push objects and creatures away without Lydia having to get into the middle of a fight.
