She can’t use it if she can’t cast. TB can raise the refresh on it, also he can stun her and freeze her. He can also lower her mana regen 10 sec at a time. The tradeoff is that you’d have to play an Ice TB and that’s no fun for anything but screwing with Sedna, QoT and Erubus (for me anyway).
Regulus gets Mark of the Betrayer which can do up to 800dmg to her when she casts it. Though I can’t remember if it hits her before or after the bramble is applied.
Sedna gets 3/4/5 second silence. This can give you time to beat QoT down between recasts. Cast Time is 0.3 though, and bramble is instant, so you will need to time and wait 5-6 seconds after she casts it to use silence on her, since bramble has a 7 second recast.
Erubus stuns, but they have a 1.0 second cast time, so you’ll need to do the same thing here, time them for when her bramble cooldown should be popping. Of course, she can chain cast it much faster with -15% cooldown items and -15% cooldown flags.
There are mana items to use on her too:
Theurgist Cap has a 5% chance to reduce enemy mana/health regen by 50% 3000gold
Gauntlets of Despair 15% chance to take 100 mana from enemy 1750gold
Warlords Punisher: Clicky item Removes -400 mana from enemy DG time they are hit by the AE from this 2250gold
Deathbringer: Clicky Item Casts Silence, 5 secondduration, instant cast 30second cooldown - 20k
Her pets can do some damage to you if she’s chain casting bramble on herself, but she won’t be able to do anything but melee damage to you without using tons of mana, leaving too little for sustained Bramble.
If the game gets far enough where she’s picking up stuff like Stormbringer (which virtually gives unlimited mana in battle, unlike Heart of Life that won’t work when damage is taken), you or your team will hopfully be similarly equipped.
Besides trying to screw with her mana or casting ability there’s always good old fashioned damage: Ashkandor can help you there with x4 crits. Although it’s bad form to suggest Artifacts as part of a strategy the only reason you’d need it is if she was also similarly equipped by upper teir Art items.