In order to get a hit under those circumstances, the original roll needs to be eye/hit/crit (6/8) and the reroll needs to be eye/hit/crit.Vorpal, I think you meant 0.375 for attacker having focus and defender using R7.
6/8*1/2 = 3/8
(6/8)*(6/8)=9/16=0.5625
No, MJ is right: if your opponent is rolling unmodified dice,
Talking about the attacker having focus. If the first roll is an eye, you reroll it. If the reroll is an eye, it's a hit.