DM question: Combining DR for monsters

[Striogi]

I'm working on building what amounts to a Mythic Dracolich for my players and I've run into a stumbling block with regards to DR.

So here's the situation:
take the Adult Umbral Dragon
http://paizo.com/pathfinderRPG/prd/bestiary2/dragon.html
DR 5/Magic

Add the Lich template
http://paizo.com/pathfinderRPG/prd/bestiary/lich.html
DR 15/bludgeoning and magic

(clearly DR 15/B&M > DR 5/M, so I take the lich DR)

Add the Mythic Invincible template
http://paizo.com/pathfinderRPG/prd/mythicAdventures/mythicMonsters.html
DR 10/Epic

What happens now??

[ckdragons]

I believe this will be the stat:

DR: 15/bludgeoning and magic, 10/epic

The dracolich will use the better DR against an attack, not both.

For example, a magic mace would be stopped by the DR 10/epic, whereas a magic longsword would be stopped by the DR 15/bludgeoning and magic (ignoring the 10/epic). An epic magical mace would bypass all DR.

[Chemlak]

What ckdragons said.

Edit: also, flagged for wrong forum.

[Striogi]

Aha. I thought it combined into some kind of much more simpler single DR.

Thanks for the response!