Seems like the reaper invasion all over again. Grab some gang members and friends to help you hunt the giant leprechauns. They have enough health to allow a player from a fairly far distance to arrive in the battle scene and earn a melee.
Work together by signaling all gang members via gang pm once you/they find the leprechaun. The other gang members will find your/their position on the map and arrive to attack the leprechaun.