Creatures killed with flash-murder still have their effects trigger during battle

stikxs

Greg matched a big cascade and his first creature out was https://mtgpq.info/cards/RegisaurAlpha which creates a dino token, then he summoned https://mtgpq.info/cards/GrandWarlordRadha . So everything here has haste and attacks. Before the first attack the game asked me if I wanted to use the flash on murder. I hit yes and picked Radha. Radah was taken to 0 toughness but remained on the field for the entire attack round and triggered her mana gain when both of the dinos attacked. I can provide a youtube clip if requested, I just have to trim the video down.