TWD: All-Stars Official Forum (The Walking Dead: All-Stars)

Mode booster allows characters in specific mode to get buffed so make sure to immediately use it in the first try in each mode.

As simple as it looks, attempt to roll the attribute yellow or above ( no need to lock unless red or purple). Prey that your luck is with you and try to get speed and attack boosted. 
Depending on your main alignments and class, you might need to focus on getting your best class and alignment boosted such as unknown class. 
More experiment will need to be conducted to formulate proper attribute ranking status.