For things like Rainbow Life, each thing that would change the damage/healing applies once. Since it starts out as damage in this case, Rainbow Life applies first, making it become LP gain, then Bad Reaction turns that LP gain into damage. Since Rainbow Life already affected that LP change, it doesn't try to apply to it again.
Anonymous 30days ago
Well in the real game there are cards like gift card that increase your opponents lp by 4k so it's a good card but in duel links it's just not use able they should have added at least snatch and steal with it