If lethal damage is dealt to a creature that has been granted the listed ability by Requiem Monolith’s ability, the granted ability will still trigger.

If multiple sources deal damage to a creature that has been granted the listed ability by Requiem Monolith’s ability (probably because multiple creatures blocked that creature), the granted ability triggers only once. When it resolves, the creature’s controller draws cards and loses life equal to the total amount of damage dealt to that creature by those sources.