When monsters attack you (as it happens, in particular to healers), your spells sometimes interrupt. I haven't been able to figure out a distinct pattern of what interrupts them. The game doesn't teach you either. Sometimes monsters wail on me for dozens of swings, and I'm fine. I can take spell damage, I'm fine. Other times it just interrupts. I never know if it's safe to stand and just heal, or run to heal from a distance.

So, what exactly causes it? Certain spells? How can I tell which ones? Attacks that hit for a certain amount of HP? I've been hit by strong attacks and been able to heal though.

Also, there need to be a few more cues that your spells got interrupted. When things heat up, I find myself spamming keys just because I want to make sure that my spell triggers. Certain games use audio for that. ;3