To help with conserving your prayer potion doses, while you are in the tunnels and you are at the chest, with the last brother to kill, wait until the Brother face shows up (which is the exact moment a prayer drain occurs), then immediately drink, pray, open chest, Kill brother, loot, teleport.
This prevents situations where you drink a prayer dose, and it immediately gets drained, which could mean life and death.
Also, prayer renewal is NOT recommended in the Tunnels or against Dharok, because the periodic prayer drain will interrupt your prayer, leaving you open to KO in the second it takes to put the prayer back on. This is especially important for lower levels.
06-Jan-2012 02:15:18