Basically we bring back old things in that mode
like sweet baby DFG(because who doesn't wanna see LB with 
and DFG kappa)
Heart of balance(gold)
Pre rework 
, Every iteration of 
,
Theres oh so many to mention,and wouldn't be cool to see some old fun stuff comeback?
BattleOxe1 votesBlitz with point and click Q from beta?
Lady Hammerlock1 votesBlitz with point and click Q from beta?
I suppose
ZT Xperimentor1 votesDon't forget pre-rework mordekaiser & xerath; and several items, from atma's impaler to force of nature.
Ryzing2Diamond1 votesI'd be okay with this. # the champion reworks in the champion select. I'd do it just to play unlimited Ryze again for a bit, I mastered pre-re-rework Ryze (The one right before this rework, in his nerfed state) and wanted to know how good i'd be with that level of power in comparison to his nerfed state.
The biggest problem is they can't account for every champion balance adjustment. It would take ages, and to be honest most people would just play release TF or Xin Zhao.