What causes Dark Arts to end prematurely?

[DemBones]

I just had my first Tainted Judas run and it seemed like Dark Arts sometimes ended prematurely causing me to take damage. I managed to kill Blue Baby and went to the Void. I was a little low on health so I tried to farm health (had prayer card) but I ran into a few situations where it would end early and I'd just take damage. Does anyone know why it ends early sometimes?

[unendingEmpathy]

If you shoot at all you end the Dark Arts thing prematurely

[DemBones]

Thanks! I wish I could say I'd never tried to shoot while using it but I just can't. It started happening more towards the end of the run and mostly on bosses, so it seems reasonable I might have been trying to shoot them ASAP without realizing it. Thanks again for the help.