Special Game Mode: Each Team Bans an Item
It would be an interesting version of summoner's rift if each team could ban an item before drafting champions. If something builds out of a banned item, you can still build that item but you have to build it all at once. That is, if boots are banned you would have to build greaves directly from the attack speed dagger all at once.
Strategic Depth and Variety
This would add so much more variability and strategic depth to the game. Oftentimes the game grows stale because off-meta strategies, compositions, or teams are not viable. It easy easy to learn what champions and compositions are optimal and you don't need to think for yourself. Banning champions does little to change this. Banning an item would require individuals to think more strategically in champion select, when building items, and when playing team fights. Thus, allowing item bans would contribute to the much vaunted strategic depth.
Avoiding stale OP items
Also, just as certain champions sometimes break the game, certain items also sometimes break the game. Banning champions allows players to avoid that annoyingly broken champ. Banning items would allow players to avoid entire classes of champions that abuse that annoyingly broken item. For example, there was a phase when triforce was ridiculously op. corki, ez, jax, and their ilk would abuse this item. It was terrible (unless, I suppose, you were playing corki, ez, or jax). Some people would argue that many current items are annoyingly broken, like last whisper.
Example with Last Whisper
In fact, let's consider last whisper. Riot concedes the item is overpowered, but they neglect nerfing for a fear of repeating the unkillable tank meta in season 2. I can understand why nobody would want tanks to be unkillable every game. But it would be fun if every now and then tanks were much stronger.
It would be interesting. Tanks would be much stronger versus AD. Teams would adjust their playstyle in response. First, teams might choose hypercarries like kog'maw or vayne who can succeed without a last whisper. Or they might eschew ad carries all together. Wouldn't it be fun if, on occassion, a no adc match were optimal? I admit it would be better to have adc's always optimal than never optimal, but it might be better to have a few games where adc's are not optimal. Second, teams would have to choose tank-busting ap champions. Akali and Ahri are not tank killers; casseopeia and karthus are. So if you are sick of the assassin meta, banning last whisper would fix that problem a lot better than banning a few FOTM assassins. Third, teams would shift composition away from AD and towards AP. Sick of the all ad meta? Sure, it's better to have one ap champion, but when all the ad's build lw, and maybe a shiv or a bork, all ad teams can be quite powerful. Personally, I am sick of that. When I go against an all ad team and build exclusively health and armor, I should feel rewarded for that. Instead I often find myself dying about as fast. Fourth, teams would choose tankier champions to capitalize on their higher effective resistances. Do want to play tanky champions but can't because they are not viable in the current meta? Well, now is your chance to select malphite, cho'gath, mundo, or nautilus.
** Other Examples **
An infinity-edge ban would similarly hurt ad carries, while retaining the effectiveness of ad casters. It would be fun to think of how to deal with that in a game, to improvise workarounds.
A voidstaff ban would similarly gimp mage's late-game tank-busting power - sort of the mirror image of a last whisper ban.
A deathcap ban would gimp ap carries in general, favoring tankier ap carries like swain.
A BORK ban would favor health-stacking champs.
A ravenous hydra ban would hurt ad bruisers, and especially their split-pushing power.
A zhohnya'a ban would hurt a subset of ap champions, like fizz or fiddlesticks. If you have a core build with zhonya's and choose to play that champion after the zhonya's ban, you must improvise your build (sorry mobafire users).
Other Benefits
While I envision this as a special game mode, it would certainly make competitive play more interesting. If all the pro games are starting to look the same, it's because the pros are very good at discerning optimal strategies for a given patch. Banning certain champions creates a little variability, as do pocket picks. But the games would be enormously more varied if certain items were banned, because it can completely change the game.
One final benefit of allowing item bans: Riot would get feedback on what items players find obnoxious. I imagine they decide to nerf champions in part when those champions are perma-banned. They'd probably learn they need to nerf certain items if those items are perma-banned.
Thoughts?
would end up perma-banned, while
and
would be juggled between until people realize that