I think there should be Legendary items.
We've all been in those matches that just drag on.. and on... and on..... You end up with a full build at 20min and the only thing left to do is sit on the thousands of gold you continue to gain, while everyone you outscaled is slowly catching up to you. Then at 30min, 40min, 50min... you've changed your build several times and the match still hasn't ended.
Solution: add Legendary item upgrades. I think at the 20min mark, Legendary item upgrades should become available. The enemy team had a chance to surrender, and now it's your chance to crush them.
Maybe don't do Legendary upgrades for every item, but the core items with passives, yes (Infinity Edge = Perfect Infinity Edge with increased crit damage; Rabadon's Deathcap = Perfect Rabadon's Deathcap with increased AP%). The upgrades don't have to be OMFGWTFBBQ overpowered, just something to add an edge to those who are carrying their team super hard and deserve a little bonus for their efforts.
Not only does this speed up matches for those hard-carrying their team, it gives everyone something else to do instead of playing the waiting game for a champion to be out of position in team fights. ALSO, you don't have to feel like you've "capped out" once you reach a full build, which is the real purpose behind this proposal. You can only re-itemize so many times during a match before it just gets boring..
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: 3800g
: 2500g
: 3200g
: 1475g
: 2300g
: 2800g
,
, with 835 gold having gone to potions and wards.