Currently, it does not stack with Eternal Soldier's Way of Lightning or Revenant's Shadow of the Wolf (and any other land-based movement skills that I'm sure I haven't mentioned).
I suggest this be changed so that it does apply to those skills, such that moving over mountain tiles with Way of Lightning + Athleticism results in a 0.5AP cost.
Athleticism
Re: Athleticism
+1
A Parrot with a Blade - Melee/Touchcaster Holy Champion || GrayScimitar - Heavy Sword Tlac IB || RustyWire - Gunwiz
Re: Athleticism
Promote.
Katerina Hasheen - Necromancer Advocate, champion of a better Hashaa
Serena Hasheen - Sword Revenant, Freedom Array booster
Isabel Hasheen - Gunwizard Councillor, infusion's #1 fan
Kandarin - Unformed potential, Crusader, fontnet architect
Erduhr-Khazai - Fire-breathing Dragon DO, Evil Overlord, pillager of planes
Serena Hasheen - Sword Revenant, Freedom Array booster
Isabel Hasheen - Gunwizard Councillor, infusion's #1 fan
Kandarin - Unformed potential, Crusader, fontnet architect
Erduhr-Khazai - Fire-breathing Dragon DO, Evil Overlord, pillager of planes