Board Thread:General Discussion/@comment-28739148-20171211033712/@comment-156.145.82.174-20180830145047

Banishing the highest level creature guarantees a chest will drop every time. Banishing the mid-level creatures results in a chest around 25% of the time and closer to 10% for the low-level. So the coin investment means you get proportionally more chests for the same number of banishment items.