Waterbending allows you to reduce the cost by by tapping a creature or artifact you control, and you can do this as many times while paying the cost
Looking at the data gathered by the community so far, this does ring true
This means that, after initially being cast, Kroxa's controller will never be required to pay Commander Tax, as Kroxa can merely be cast from the graveyard.
Thraben Inspector and Inspiring Overseer will both draw you plenty of cards, while Gallant Cavalry will make you lots of creatures
Sisay, Weatherlight Captain is the legend of all legends, and her ability to search the deck for Legendary cards and put them into play makes her the perfect Commander for this deck full of them - including all the Shrine cards: Hondens, Sanctums, and Go-Shintai's, which allow the deck to incrementally grow into an enormously powerful machine generating massive value each turn
The Spike Considering how little attention Green Goblin garnered in Commander leading up to Marvel Super Heroes, it used to be quite cheap