hmm... someone mentioned Hero_Touch_Trigger above =) =) Now everything is clear.
although, not quite...
Added 26 minutes later
great, I found the error why the megamonsters were losing. It turns out that under AI control, something is wrong with their stats. Apparently, there's a limit. 100 centaurs were dealing 1,000,000,000 damage per shot, although the panel displayed this damage as 1!
RedHeavenHero - could you write a script to determine if hero 1 has the Mask artifact and, when attacking hero 2, equalize their stats? I would be very grateful.