Doesnt it do magic damage?

It does magic damage.

It does magic damage, and it's just as easy to balance as an item that gives you temporary invulnerability or an item that slows with every autoattack. If it's too strong, they'll raise the cost or lower its numbers. If it's too weak, they'll do the reverse.

Well, my mistake on the true damage comment. But it is insanely overpowered and everyone knows it. If you think it is balanced, you probably thought Rengar was balanced before his nerf (despite still being OP).

It's not balanced. Nome has made it very clear that it wasn't intended to be balanced so it's effects could be evaluated, since PBE isn't really an option.

It's getting nerfed. That has been made clear as well.

As I say in every related thread I come across; the problem with BFT is the fact that it applies on damage instead of when a spell lands. The difference being that a single DoT spell will apply twice as much or more damage than a direct damage ability.