2-Harpy.
3-Cerberus.
4-Vampire.
5-Gorgon (to kill level 7 creatures).
6-Naga.
7-Hydra.
Of course, all of them are upgraded.)))
This is the ideal defense for a Castle.)))
Yes, yes, not the infamous bunch of archers, but monsters whose attacks have no counter; you wait for your turn, then come out of the Castle, attack, and fly back.)))
The Gorgon is designed to kill level 7 creatures that have flown over the walls.)))
For the attack, I would take the following group (Assault).
1-Centaur.
2-Storm Elemental.
3-Griffin.
4-Ogre Mage.
5-Dryad.
6-Cyclops.
7-Skeleton Dragon.
It will take a little longer to deal with them...
Centaurs are very fast and among the strongest at this level...
The Storm Elemental is an archer and also the strongest at this level...
The Griffin will be useful for flying over the wall early and stopping the defenders. It will take on 1-2 archers and another 1-2 enemy warriors, which is enough and should be enough for your troops to climb over the fence (provided you have a good ballista or Cyclops).
The Ogre Mage can fight well and cast spells.)))
The Dryad can bind a squad that has imprudently left the Castle (and then your entire horde can attack it).
The Cyclops can destroy the wall and is also an archer.
The Dragon is for flying over the wall in case the enemy has many archers. And old age is a very useful thing in an assault.
In ordinary battles, they are all good in their own way.)))