I think back to how stupid Yargle and Multani looked at first, yet it ended up doing nothing in March of the Machine
Eventually, you reach a critical mass of shrines that give you a massive resource advantage to win, be it making everyone discard lots of cards with Honden of Night's Reach or milling opponents with Go-Shintai of Lost Wisdom
That said, there is an easy way to get the 20-charge-counter win with Darksteel Reactor in Historic, but I don't think you're going to like it: you simply play Darksteel Reactor as the win condition in your Nexus of Fate / Wilderness Reclamation deck
These are not directly mana doublers, but they allow you to build a massive mana pool by floating your mana each turn and saving it
This here is Sygg, Cutthroat by the Rivers
Gigantosaurus $1.99 This card is the best excuse Ive had in ages to link you to my favorite video from the early YouTube era