No one called me for the Von Leon questions? :(
He only uses the heal move when castle golems are in range, and he can use it throughout the fight (he has used as early as 1min in to the fight, and as late as 30sec left on the clock [damn golem was hiding >>>> the whole fight]), but he only heals when castle golems are spawned and in range, and it is 10m hp per castle golem.