How about if you have spellthiefs/frost-fang/Frost queens. You cannot purchase lichbane, and vise-versa. It's a small step to help keep mage supports damage down, and to prevent some mid mages from building Frost queens as riot is trying to stop this.
BluePolarizer2 votesLich bane users other than Sona and TF don't buy Frost Queens.
Omega T33mo1 votesTeemo frost queens and lich bane...?
BluePolarizer1 votesif Teemo wants to get rekt midgame, sure np.
LatetotheRace1 votesEkko, Diana, Fizz. A lot of people buy Frost queens because of it's affordable stats.
BluePolarizer1 votesYou can most definitely suboptimally take a gold generation item on Fizz, Ekko and Diana that gives them mana regen that they don't need instead of a major powerspike item. It just won't be very good.
LatetotheRace1 votesI tell ya what, I'm a reasonable man or at least I like to think so. So I'll ask ya, why exactly are you so against this? If a lot and I mean a lot of champions are building this item combination, namely mid laners, then I think this is a viable solution. Bare in mind though only 2 or 3 supports (
, and maybe 
or 
)would consider building lich bane, so in all reality no one's really missing out. (And hey, if they do this then they'll probably buff Sona, and pretty much everyone want's that. No sarcasm)
BluePolarizer1 votesI don't like arbitrary and narrow restrictions. It is, to me, a very unelegant solution. Why not deathcap and FQC? Why not Zhonya's? Why not sorc shoes? Why not have more of these such as only Lee Sin can buy Hydra, but only after doing golems 5 times? Does shit like this make sense? Why LICH BANE of all items?
Right now I'm seeing less mids take it anyhow. If it's a 50% win rate item on mids with a sub 50% buy rate, is that a problem?
LatetotheRace1 votesYou're obviously missing the point. Lich bane is an item that enough mid laners build that almost no supports do, so there would only be one real confliction between the two. Do I want a long term solution? You bet your ass I do, but since we don't want to destroy supports anymore than we have recently something is going to have to give mid lane. Your question on Deathcap? It's not an item supports build, and zhonyas is the same (unless they have a 100-0 assassin), and god knows supports need that possible boost from sorc. (Btw the tangent on lee was irrelevant and didn't add anything onto the argument.) Again, I want a permenant solution so it's probably going to boil down to not letting certain champions buy certain items, I can almost promise you this is going to happen. You don't like it, and I don't much prefer it either, but that's what's going to have to happen.
ZephyrDrake1 voteswhat is the point of this? this is a very stupid idea that will never happen... ever
LatetotheRace1 votesExplain your position if you wouldn't mind.
ZephyrDrake1 votesExplain your position if you wouldn't mind.
what is there to explain? Lichbane and FQC doesn't have any synergy at all. One slows and the other enhances your next auto after using an ability. All this would do is hurt a very few amount of champions who would care about building both at the same time for no reason whatsoever. If mages want to build FQC then they should be allowed to, when FQC is the only decent AP+CDR item right now due to it not being niche as all hell then there's an issue with the rest of the CDR itemization for mages and preventing them from building FQC isn't going to solve the problem but make it worst.
You look for what is the cause of the problem and fix it instead of just making the problem worst by doing dumb limitations like this one