Basilisk and PhoenixI don't think a phoenix/phoenix tears would be able to help with venom. It could probably close a bite wound, but not neutralize/purify poison. If you had a unicorn or other creature of purity then that would work, but healing does not remove poison. I don't know if phoenix tears would help with petrification or not, but I kind of doubt it. The whole insta-kill thing... Sorry, phoenixes can't help you there.
