They must win masters

At least 80% of the mana to win must have come from trader bonuses

That is, if you take the required profit to win, trader bonuses they got are at least 80% of that

Example

• Person A wins with 140k profit in the month

• Second place B has 56k

Winning requirement is 56001 mana. As long as A has at least 0.8*56001 mana in trader bonuses, it counts as a trader bonus win.

I say this to not disqualify situations where someone has high bonuses but also high profits.