The strength and size of your combined army depends on the overall Offense and Food Consumption of the participating Units. The Offense of a League Attack can be increased by one of two things: one-time League Attack Offense Boosts, or the 12 h. League Attack Boosts. Both of these can provide either 10% or 25% Offense increases. The 12 h. Boosts can be applied up to three times in a row, totaling a cumulative 36 hours before another Boost can be used
The number of Units that can join a League Attack depends on the upgrade Level of the “League Attack Army Size Limit” Lost Art of the Attack initiator. The further you upgrade the Lost Art, the more Units can join your Attack.
After upgrading to Level 18, the player will unlock the ability to send their Attacks before the dispatch timer runs out, while Levels 19 and 20 each grant an additional unlocked League Attack Slot to Attacks.