Four Leaf Clover
Feeling lucky? You should! With the Four Leaf Clover perk, each hit in V.A.T.S. has a chance to fill your critical meter.”— Fallout 4 loading screen hints
Each successful hit in V.A.T.S has a chance of filling the player's critical meter. The first ranks gives a chance; the second rank gives a better chance; the third rank gives a very good chance; and the fourth rank gives an excellent chance of filling the critical meter.