How does celestial mantle interact with tainted remedy if I attached it to an opponents creature?
That player would die as soon as that creature dealt combat damage to a player. Life setting effects like celestial mantle or oketra's last mercy actually cause life to be gained or lost equal to the total change, so doubling life would be gaining life equal to their current total, so your opponent would lose life equal to their current life total and die. Hope you have Fumiko the lowblood to make them attack though 😆