A new way to balance the game.
Take these legendary items like Infinity edge and make them unique in the game. Only one champion can have IE. The first adc that buys it is the only one that can build it. If the enemy team gets Infinity edge you better hope your top laner gets randuins first.
If you do something like this and dont let players that get ahead simply start buying multiple legendary items (cap the number of unique items a person can have in inventory) you can make these items empowered enough to be game changing as you want them to be (esp since only one team can have the item) without making the game too snowbally.
Right so make them overpowered if you want. Only one legendary item of a given name in the game. Only a champion with ie can crit strike. Thats really powerful to have because of the denial to the enemy, but its the only legendary item you can get. The rest of your build synergises with it, but cant make you game breakingly powerful. Then, include legendary items in the ban phase of the game and you have something going. A game where randuins is banned but ie isnt looks one way. A game where thornmail or warmogs is is open, but BT and bork or mortal reminder isnt looks another way.
Some games will see opposing laners contesting hotly over a core item. Others will see two laners go for different things because of choices in draft phase. There will be strategies such as the above mentioned randuins, infinity edge paring. If your team gets both of these then its almost gg. The other team has no defense against crits and has none of their own to play around. If it works the other way and randuins opposes infinity edge then ok theres that. Look for advantages in other lanes.
