Instructions
Go to Soluna City and click on Braddock Steele in the St. Patrick's Day War area. Accept his quest "Psycho-Rainbow Attack."
Walk up one screen past Braddock Steele to find the Rainbow Vortex. One of 15 possible random monsters will appear. Defeat the monster with your character's various combat abilities. If you happen to encounter a Lucky Warrior, which looks like a leprechaun, for this fight it will drop a Clover.
Repeat the quest as many times as you would like to increase your chance of collecting Clovers. For every 10 Clovers you collect, you will gain a rank in the event, with a maximum number of 70 Clovers collected. After collecting 70 Clovers, you will achieve the rank of "Ultimate Commander."