Bestow Hope: Beginning at 1st level, an invigorator is a champion of her faith who can call upon her deity’s holy power to bathe battling allies in protective energy. As a swift action during combat, the invigorator can choose a number of nonevil allies within sight equal to her Charisma modifier upon whom to bestow hope. Once activated, bestow hope grants the invigorator and these allies DR 1/— until the combat ends, at which point the damage reduction immediately ends.
The DR this ability grants does not stack with the DR the invigorator receives from aura of righteousness or holy champion.
Against:
DR does not stack unless it says it does. This ability has no such language.
For:
The line about not stacking with two abilities is absolutely meaningless unless it stacks with others abilities. Since it explicitly does not stack with those two it is implied that it stacks with others.
No, it does not stack with oher DRs. It specifies your available abilities because they are both yours. Various barbarian archtypes, and other class options that can get DR from multiple class abilities also state they do not stack in the same way. This is specific clarification to make it clear to players.
DRs against the same thing, do not stack. Having DR5/evil and DR1/- does not give you DR6/evil, nor would it boost an Invulnerable Rager's DR#/-. Only the most powerful ability is used. As a character who can have multiple DR sources, each source will generally have the line that it does not stack with your other sources.
