Per tier is a common way of saying an effect is at normal power in the heroic tier, twice as powerful in the paragon tier, and three times as powerful in the epic tier. It commonly applies to damage and attack roll bonuses, and other effects granted by feats, powers, class features, etc. Saying "+1 per tier" is much easier than the longer explanation. Examples: * Sneak Attack adds 1d6 damage per tier. This means at level 11–20 it deals 2d6, and at levels 21–30 it adds 3d6. * Weapon Focus adds +1 damage in the heroic tier. This increases to +2 damage in paragon, and +3 in epic.