Thorncoat fires when something hits you. On a piece that carries it it reads: Taking a hit has a {chance}% chance to lash out for {value}% of your Power at enemies within 2 u.

Word for word it is Taking a hit has a {chance}% chance to lash out for {value}% of your Power at enemies within 2 u, and the number in it grows with the gear: 60 to start, 3 more for every item level, at a 25% chance.

0 bases carry it.