Zombie Outbreaks

にゃんこの世界にもゾンビが襲来！？

Zombies also attack the world of Battle Cats!? - Event Information.

Zombie Outbreaks (ゾンビ襲来 Zonbi shūrai, Zombie Attack) are a special event that appears after the player has cleared Chapter 1 of Empire of Cats. This event was added in update 5.6 of the Japanese Version on November 16th, 2016. The 5.7 update introduced Zombie Outbreaks to Chapter 2, and 5.8 introduced Zombie Outbreaks to Chapter 3. Update 7.4 added new outbreak stages to Into The Future.

Explanation

This event introduces a new type of enemies - the Zombie Enemies. Zombies can burrow (once, though some can burrow infinitely and others none) past the player's cats' hitboxes and they respawn once (but some infinitely) at 50% or 100% health, they also appear in some events and late Stories of Legend stages.

When defeating a stage with a Zombie Outbreak happening, the player gains a little "Z" medal by the stage's name, as well as gaining 10 Cat Food.
If the player completes all Zombie Outbreaks in a specific medal set, the chances of getting a treasure in those levels significantly improve.
If the player completes all Zombie Outbreak levels in a chapter, the Energy Capacity will rise by 50.
At first, Zombie Outbreaks appear once every few hours, but they get significantly rarer once the player has completed most of them. If the player uses the Energy Glitch, they occur more easily.

The different Zombie Enemies that can be encountered in Zombie Outbreaks are:

Zoge (Zombie) - Zombie Woof (ゾンビワン, Zonbiwan)
Znache (Zombie) - Nyororon (?) (にょろろん)
Zomboe (Zombie) - Hippotarian (カバタリアン, Kabatarian)
Zigge (Zombie) - Tonsey (トンシー tonshī)
Zackie Peng (Zombie) - Jackie Peng Z (ジャッキー・ペンZ, Jakkī pen Z)
Zory (Zombie) - Gori Jun (?) (ゴリ・ンジュ, Gori.n'ju)
Zir Zeal (Zombie) - Sir Seal Splash (ブチゴマさま, Buchigoma-sama)
Zang Roo (Zombie) - Skull Boxer (スカルボクサー, Sukaru Bokusā)
Zroco (Zombie) - Croco Bond (?) (ワニボン, Wanibon)
Lord Gravey (Zombie) - Gravey Hand Tarou (墓手太郎 Haka-te Tarō)
Miss Haka (Zombie) - Gravey Hand Hanako (墓手花子, Hakate Hanako)
Cadaver Bear (Zombie)
Dread Bore (Zombie)

Interestingly enough, the zombies in zombie outbreaks in Chapter 1 are magnified by 20%, making it easier for new players to farm cat food. In Chapter 2, the zombies are magnified by 30%. In Chapter 3, the zombies are magnified by 50%.

Most enemies in an "infected" stage will be replaced with Zombie Enemies (with some exceptions), bosses still appear like normal if the original stage has one, or being replaced by its Zombie version.

Strategies

A level 20+ Crazed Giraffe Cat can prevent all peons from burrowing. Spam them to bypass all Zombies and destroy the base.
For an even faster method, use the Crazed Cow (or the Cat Cannon) to clear a path for Awakened Bahamut to destroy the enemy base in one hit.