None whatsoever. Conqueror is ridiculous and turns otherwise normal champions into extremely problematic ones:
* Tryndameres take Conqueror and play around RNG crits for a million at early levels.
* Yasuo takes it and keeps it ready to proc until he builds up a full shield, and then pushes the enemy laner out of lane entirely.
* Renekton abuses his cooldowns with it and that somehow does not make him MORE of an offender of Conqueror than the previously mentioned carries. Just look at this rune and then look at Renekton's kit, like holy crud.
* Irelia, Jax, Camille, etc. abuse it alongside their CC and mobility for pretty broken all-ins.
* Other broken things done with it in pro play that I don't bother to research. You know better about it than I do as I fall asleep trying to watch the LCS right now.
None of that is fun or engaging to play around, and to make matters worse it is a rune that scales extremely well into lategame. That should not be the lategame fantasy of melees - the opportunity to burst someone like an assassin by abusing certain defensive abilities or despite building tank items. Tanks already try to do that now anyway to stay relevant in this meta, so Conqueror just makes bruisers better tanks than tanks, save having as much CC. _But then again, killing is pretty good CC..._
**Let's nerf Conqueror to the ground already, or at least change it.** Even 10% of damage becoming true damage would be somewhat egregious alongside that amount of scaling AD, but at least that sort of nerf would leave room for some more interactive stats, like 5% damage reduction and 5% bonus healing or something along those lines. Those sort of stats honestly make much, much more sense thematically than just more raw AD and 20% of damage being true damage - a rune that enables warriors to emerge triumphant through the thick of battle, not "LUL I INSTAGIB U NAO". Despite being less broken I would consider taking that rune over the current monstrosity that it is. Rito pls.