To avoid training 5 star units they have to be removed when you want to start your training.
The process to remove the 5 stars from lineups and add new units and start training followed by adding ba… ((more))
Thresher has low hp as mentioned and is in the front with tank.
A unit with aoe dmg kills him quite fast (like BFG or gryphon) while attacking the tank.
The bomber unit can also be countered, by… ((more))