Gladius Legis
Legend
Yes, I was rushed and my math was off. What's your excuse for failing to get the point? There are tons of creatures at CR 6 and lower that have ACs of 16-18, 40-50% miss chance. And some that are higher than 18.
I got your "point," the problem is that it isn't much of a point.
Even if your miss chance is 50%, you still only have a 25% chance of missing with both attacks. Combine that with the 20% chance of failing a CON save, and your chance of losing the spell before you get to try for it again in Round 2, if you're only hit once, is 5%.