Right after my last post, I got destroyed... using my own strategy!
This only means... there is a better strategy for battles that are ~13 Mana and using Thaddius Brood.
Check it out.
The Cursed Windeku stays as your tank, but instead of placing the Crypt Beetle or the Undead Badger as your next monster, you place Life Sapper and Carrion Shade in that order.
Life Sapper with add health to itself after each of its attacks, therefore it will outlast your Crypt Beetle or Undead Badger. The Carrion Shade will block the Undead Badger in case your competitor moves first.