Soo.. what the point of beating that boss ?
Extra sun medals ? Coz I tried it only once so far, ended in a Draw, got some currency and I think Sun Medals.

If its not something that is required for the event itself I dont really care about smacking him that much to be honest, unless of course if you smack him XYZ times, at the end of the event you get something neat (a fluffy plus toy of the giant centipede guy for you garden would be kinda adorbs :3 )