So I attack with {Battering Krasis} that is a 5/4 and a {Druid's Familiar} that is a 4/4 and a bunch of other creatures. The opponent only has {Boros Reckoner} to block. He says he blocks the {Druid's Familiar} to deal 4 damage to {Battering Krasis} before it deals lethal damage. I said all damage is dealt simultaneously so the trigger wouldn't go off till after all combat damage is dealt.
Who is right?
You are, unless your creature has first strike.
You are absolutely right.