Actually, that's where the prescience comes into play. I hold no illusions that physical ability and acting will solve everything. That's not what makes her overpowered.
The way it works isn't like future sight, but rather an instinct to topple destiny itself. It's like a cold wind blowing inside her, striking with the force of a an arctic gale for the most cataclysmic of threats. It also warns her what direction the threat is coming from.
From 200 yards, in a well cloaked spot, without magic, just a single bullet, little Liliana is no more.
This exact situation happens later on, at a point where firearms begin jumping from pre-industrial era to WWI type gear. Her prescience hits the moment before the bullet and she jumps the instant before it hits, giving her enough time to bring up the protection of what is best described as a parasitic armor with a symbiotic relationship. If you don't care for my explanation on that just skip the next block of text.
Basically, when they realize that attacking directly won't work, someone tries to trick her into coming in contact with what can be best described as a parasitic armor. It's a living, regenerative material that hardens by drawing on the wearer's own life. It protects them, but can't be removed and will kill them in a matter of days. The thing is, this enemy was himself tricked because the parasite was literally made for someone identical to Lily eons ago. It can feed off of the disruptive energy of her aura instead of her body. However, excessive use of the hardening ability accelerates her mental decline because of the energy needed to fuel it.
Ramblings aside, back to your response.
Alright, but that can turn on her in the blink of an eye if someone realizes they've seen her before and blows her cover in the middle of a group of enemies.
Assuming Liliana actually gets caught in such a situation (and she does), there are a few factors to consider. In a confined corridor, she can release a singular disruptive burst, exhausting that energy but knocking out everyone in the radius of an average bedroom. In an open space, there are points where she is forced to literally use enemies as stepping stones to reach rooftops and escape.
Poison her and watch her choke while I give her a little finger twiddle bye-bye wave
This is another part that can be considered bs, but again with the prescience. If Lily is about to do something dangerous or something is about to happen, she senses it beforehand and "shatters that path of fate." However, you might be able to force her to ignore the screaming wind within her and go into a cloud of poison or disease if a friend is trapped within.
My story ramblings aside, you have very good points that, for any other character, would be completely valid. The key factor is the element of surprise and deception, something that this girl is rendered immune to by a power that is guaranteed to eventually destroy her sanity. The best way to go after Liliana is by targeting with her and forcing her to go into danger of she doesn't want them to die.
Anti Magic and danger sense alone are ridiculously OP on their own, but the combination of the two is what actually inspired the story I'm writing so I want to work with it.