Some games, including Dungeon Crawl (example), use a balancing technique that attempts to prevent certain values (stats, damage, etc.) from being excessively high. The algorithm looks like this:
if value > 20:
value = 20 + (value - 20)/2
#70 → 45
...and can be applied multiple times:
if value > 20:
value = 20 + (value - 20)/2
if value > 40:
value = 40 + (value - 40)/2
# 70 → 45 → 37.5