If lethal damage is dealt to the enchanted creature, Pain for All’s last ability still triggers.

If the enchanted creature leaves the battlefield before Pain for All’s second ability resolves, use its power as it last existed on the battlefield to determine how much damage is dealt.

If the enchanted creature is dealt damage by multiple sources at once, such as by two creatures blocking it, Pain for All’s last ability triggers only once. When that triggered ability resolves, the enchanted creature deals damage equal to the total amount of damage dealt to it to each opponent.