Wearing a shield of mobility should confer SLASH-style free action: rather than paralysis resistance, you instead have a decent chance of freeing yourself if you get grabbed by a monster or attacked by a mind flayer.

Ice devils should have a slowing attack, like they do in D&D. Most likely, this should be like a lichen’s temporary slow in EvilHack, rather than a permanent speed-loss like a shade or skeleton has. Free action could reduce or negate this.

Randomize the set of “critical” extrinsics and the base items that provide them in each game. I.e. instead of every game having a cloak of magic resistance, ring of free action, and amulet of reflection, the game could have a ring of reflection, a cloak of free action and an amulet of magic resistance.

A potion or spell of free action, which gives it as a temporary intrinsic, and exists solely for the rare case where you are in a demonic or vampiric form and the ring of free action is silver.

Free action enables you to move on turns you would normally miss due to being turned to stone, effectively giving you more actions to save yourself.

An artifact T-shirt that provides free action when worn, but only if no armor is worn over it.