There are four types of Mecha in the Mecha Factory, if you manage to assemble all colours of one Mecha type, you will be able to unlock the corresponding Ultra Mecha of that type. We first launched Ultra Mecha Zodiac - Thug, and the corresponding monster type is Sagittarius. After you have assembled all 8 kinds of Sagittarius, you can unlock Zodiac - Thug for free in the Mecha Factory.

Level 50 Buff:

Troop Attack +864%

Troop Defense +864%

Troop Health  +864%