Tuc bleith mulind tuathbil forthu.

Tuc bleith mulind tuathbil forthu. Tuc a n-airthiur fora n-iarthur 7 a ndesciurt fora tuasciurt.

(put * grinding * of mill * widdershins * on-them . put * their * east * on their * west * & * their * south * on their * north)

He reversed the grinding of their mill. He put their east on their west and their south on their north.

In other words, he utterly confused them. The "he" in this case is Féic mac Follomuin. In the tale "Cath Ruis na Ríg" he volunteers to scope out the enemy forces for Conchobor. Then he impetuously decides, for the sake of his only glory, to cross the ford and confront the opposing army all by himself. Feic's unexpected foray sows confusion among them. Unfortunately for the would-be hero, the enemy quickly recovers and moves to surround him. His bravado fails him and tries to flee back across the river, but miscalculates his jump and
is drowned.