9 times out of 10, it doesn't die too fast for my second spell to land on it. When it doesn't, and I don't cast that spell, it doesn't die in time. It's that 1 out of 10 that's screwing me over due to allies getting unexpected crits/bloodletter procs/etc and suddenly killing it far faster than it normally dies.

There are times when I get like a Fire III crit or am in the right part of my long-term rotation to Swiftcast+Flare and no other spells from me are needed, but those are rare occasions.

And this specific problem hasn't existed until this patch. Yeah, sometimes your cast will get interrupted due to something dying before you finish, but that's not what I'm talking about. I'm talking about the spell lands, even if the thing is already technically dead, and pops up a damage value, which used to still give you your AF3>UI3 switch, but doesn't anymore. The same is true for Fire III switching you from UI3 to AF3, though this is far more uncommon a thing to have happen. It drops the buff you have, but doesn't give you the buff you're trying to get. It's part of what they did to get rid of infinite flare, as far as I can tell.