Huh, so looking into Arkaim's neat discovery about the Reflexcoil pants… did some experimenting with running away from writhing masses. Up until five minutes ago, I thought that if a mass grabs you, you are held on to until you either win or lose the fight (no running away ever).
But, it turns out — evasion can "release" the hold the mass has. Eg. if mass uses Drag to Maw which isn't avoided — can't run away anymore — but then later that fight, you use evasion vs. the drag to maw, it gives the "avoiding its grasp" message and you can now run away again.
(I have often wished for this but it somehow took five years to figure this out…)