If a character receives DR from 2 different sources, do they stack? For example, a cleric receives DR 3/- from the Earth domain. That same cleric casts elemental body iv on themselves, which provides DR 5/-. Does that cleric now have DR 8/-, DR 3/- then DR 5/-, or DR 5/- only?
No they do not stack, unless the explicitly say that they do. The only one I know of off the top of my head that does so is Armored Juggernaut Fighter Advanced Armor training that gives DR/- that stacks with its armor mastery and adamantine armor.
no they do not stack like that however they do stack in a way that if you have dr15/bludgeoning and magic and dr15/piercing and good you receive dr15/bludgeoning and piercing and magic and good
What I learned from my very short time playing DnD is that if you have to ask "do they stack?" Then the answer is no .... there's very little that stacks in this game I learned
Sorry, I was apparently distracted when creating this post. Thought the DR 3/- was from Earth domain. Not! On this cleric, it's from him wearing adamantine full plate (DR 3/-) and will cast elemental body iv (DR 5/- as huge earth elemental).