Let’s compare it to Loki. Loki needs to fight a lot to get a “free” myth unit, and that unit is always from the current or previous age.
Shennong, on the other hand, gets myth units passively, and they are always from the next age, which makes them much harder to deal with.
Free myth units represent a huge amount of resources, especially if we consider the current patch with a reduced villager production rate, and in shennong case the player receive a bonus with a risk as fighting like the loki need to do
My suggestions:
- Make it work like Loki: myth units should only come from the current or previous age.
- Reduce the myth unit generation rate, with a slight increase as the game moves into the late game.