Desert Wind Rage's passive effect is that you deal 5 + Strength modifier damage to all enemies within 5 squares at the start of each of my turns. If I have the feat Deadly Rage (Player's Handbook 2) and/or the utility power Strength of Enduring Pain (Primal Power), will their increases to damage effect the Desert Wind Rage aura?
I.e., 5 + Strength modifier (6) + Deadly Rage (2) + Strength from Enduring Pain (10) = 23 damage to all enemies within 5 squares.
No, Desert Wind Rage's passive effect does not benefit from damage boosters
From PHB2, pg184 (emphasis mine):
Deadly Rage
Benefit: You gain a +1 bonus to damage rolls while raging. ...
From PP, pg18 (emphasis mine):
Strength of Enduring Pain
Effect: Until the end of your turn, you gain a bonus to damage rolls equal to the ongoing damage...
Both give a bonus to damage rolls. Desert Wind Rage's passive effect does not roll damage: 5 + Str is a static value. Thus, Desert Wind Rage's passive effect does not benefit from Deadly Rage or Strength of Enduring Pain (or almost any other damage boosters; pretty much all of them increase damage rolls).
