An opponent controls an indestructible creature, or you have a way to give an opponent's creature indestructible.
You have a way to deal damage to the indestructible creature.
Steps
If needed, cause a creature an opponent controls to gain indestructible.
Activate
Requiem Monolith by tapping it, targeting the indestructible creature.
Deal damage to the indestructible creature.
The creature triggers, causing its controller to draw that many cards and lose that much life.
Orcish Bowmaster triggers for each card drawn. Resolve the first trigger, dealing 1 damage to the indestructible creature and causing you to amass Orcs 1.