The loot bonus will be given after each successful attack, meaning that you have to get at least a one-star victory to be awarded with the loot bonus. The higher the league you're in, the bigger the loot bonus you will receive.
Also, loot bonuses depend on how much damage you inflict on your opponent -- big wins, big bonuses:
1-50% damage: f
or every 1% of damage against your opponent you get 1.6% of the total league bonus.
51-70% damage: you earn 1% of the total league bonus.
For instance, 25% damage gives you a 40% bonus, 50% damage gives you 80% bonus, and 70% damage gives you 100% bonus.
To be eligible for a bonus in the first place, you need to already be ranked in a league. This means that the bonus will not be awarded if the victory is the first one of the