by Mike Shea on 10 October 2011
While most math in 4th edition scales linearly, player power scales on an increasingly steep curve. While monster damage increases by about 1 point every level, player healing increases even faster. While an Essentials warpriest's healing word increases healing linearly, the number of times that warpriest can use the power increases as well.
When we look at damage auras, they also generally scale linearly. 5 per tier seems like the typical amount. 15 damage at level 24, however, won't seem like much when PCs are gaining an ever-increasing number of ways to heal or mitigate an ever-increasing amount of damage.
Instead, begin to scale aura damage higher as you get into the upper paragon and epic tiers. It isn't unheard of to have auras as big as 30, 40, even 50 damage a round when a battle is really scaling up. You'd be shocked at the creative ways PCs heal or mitigate this damage.
This goes for both monster auras as well as environmental effects. Powerful auto-hit environmental effects are an easy way to keep the threat up in a big epic-tier battle without increasing either the complexity or the length of combat.