When the Enemy Base's health is around 120 000 HP, Master A. will appear and serve as the boss, and Croco starts to be spammed.
Master A. is a backline enemy with a gruesome range of 451, which not many cat can outrange. Luckily, he is alone in this stage, therefore not a big threat during this stage, but in later stages he may be the cause of many defeats.
To defeat the Master A., send out cats with high stamina like Wall Cat and Bondage Cat as well as Macho Cat. Use some longer range Cats (more than his range of 451). Bahamut Cat will not help much, but he can get a hit off if lucky. Instead, rely either on super long range or Giraffe Cat.
Note: Master A. was created to counter Bahamut Cat, having only 1 more range than him. So when Bahamut Cat is charging, Master A. can hit Bahamut and cancel the attack. There aren't many Cats with a range over 451. Hacker Cat is great if you have him.
Although it doesn't live long, Cat Gang can be surprisingly helpful here, damaging Master A. and taking out peons at the same time.
Strategy 2 (ft long range attacker.)
Lineup: Tanky units, Meatshields and any amount of long range attackers (I used hacker cat.) It is not recommended to use Tesalan Pasalan as the peons will overwhelm him. An uber would help, but it's not needed
Send out two wall cats to block the peons. If one dies, replace it with another. Continue doing this until the wallet is at level 7/8 and send out your long range unit backed up by tanky units such as Titan cat.
When master a spawns, spam everything and let your long range unit slowly whittle down his hp.
You should win!!!!!