Enemy Within Campaign Homebrew Question.

If one of your party members or you in the campaign have a wood elven brother who was captivated by the bad moon turn away.

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I am looking to interweave the characters's backstory with the overarching narrative of the campaign. Are there any statblocks for chaos spawns, wood elven roster(more than just the base wood elf ex: glade riders), and eagle bolt throwers, in any released book? Additionally, how would a wood elven settlement fight against a chaos undivided chaos spawn?

I am thinking of the brother to turn into one right in the middle of it, with the players having to survive while the entire town is mobilised to minimise damage and take down the monster. The Eagle Bolt thrower I was thinking could come in after a few turns of fighting as they bring out weapons from before the War of The Beard in a desperate effort