Personally, I save Thrill + Vengeance or Rampart + Sentinel or Shadowskin + Shadow Wall for the 2nd breath while in DPS stance at i238. At lower gear levels I'd pair those CDs with tank stance.
2nd stack don't kill with Rampart alone, but healers must be on their toes.
Problem with using 2 CDs - you will not have it for next Ala Morn.