The new “Cost Efficiency” system & niche interactions with skill costs - Patch 3.29 Deep Dive

The elimination of "reduced skill costs" in favor of "increased skill cost efficiency" will introduce some niche interactions in Path of Exile patch 3.29. This video is a deep dive (pun intended) of the new cost system and how it will interact with existing "*increased* cost" modifiers that are unmodified, according to patch notes. 00:00 - Summary of patch 02:17 - Pre-patch 3.29 skill cost math 03:51 - New mana cost system math 06:32 - Interaction of "increased efficiency" with "increased cost" 08:50 - Mechanics which scale with skill costs Key art and music courtesy of GGG