We don't have a lot of actual stat block previews yet; however, here are some examples of revised old stat blocks:
- the new Empyrean does 68% more damage. It also has an auto-stun effect.
- The new cyclops can do any combination of ranged and melee attacks with its multiattack and it has the Reaction "Limited Foresight"
- The Kuo-toa was given a new reaction (I don't have that one in front of me at the moment).
The only other previews we have of existing monsters are the skeletons and ancient green dragon. The skeletons didn't change much. The green dragon changed a lot and added lots of interesting options; however, it seems like it will change based on these new newer previews.