How can i counter true damage?

I think you should focus more on the 1452 Physical damage rather than the true.

It's a Camille. Melee carry/splitpusher. The best counterplay to her is stay grouped, and dogpile on her when she engages. Unless you're playing another melee carry like Fiora, Yi, Riven etc. you shouldn't be able to counter her in 1 vs 1 in other way than buy time.

Buy health/health regen, kill the enemy quicker, evade the source of the damage, or end the game before you let Camille reach almost full build.

Hp

Stop giving riot money is the strongest counter.

Health.

Against % true damage like Vayne and Fiora, it's attack speed slows and thornmail.

her q does 950 true damage or something its not the item (late game)

if it just true dmg then by HP.If its %hp true dmg ,well then not much you can do.

Vision. Control Wards and your trinket.

Everyone's saying health, but honestly? If that's her Q damage, we haven't even factored in E damage, W damage or the follow up hits while you're stunned or slowed. Health also assumes this is late game Camille, not fed Camille.

If you know where Camille is, or you don't but you know Camille isn't close enough to hookshot onto you, she can't hit you for 1000 damage. This works BOTH late game or when she's fed. Be where Camille isn't, and if you can't do that, hide behind your teammates. I don't see QSS or Scimiar here. Let her ult one of them, then giver her the space AIDS, pop out some voidlings, and barf on her. If she isn't dead (how?) you at least cancelled her ult and saved someone.