Looks like Tier 2 dropped with the Bernie Greenback event, at least at lower levels. As some examples, it took me 18k to beat level 10 epic boss, 35k to beat level 13 epic boss, and 46k to beat level 16. (I'm on level 34 with my camper account). It did go back to the numbers on the chart later, since levels 25-28 matched the chart perfectly.