The ER tile

ER is a digraph: two letters on one tile, placed in a single cell, where they read as both letters of the word. It is worth 6 points, its own value rather than the sum of its letters.

Points
6
Its letters
E (3) + R (5) = 8

How often a bag carries one

Every bag carries a set number of digraphs, each swapped in for a cheap consonant. No bag holds the same digraph twice, and each of the 8 is equally likely.