Collect all challenger decks!
I can even see this as a powerful card in an Esper artifact shell, with a bunch of mana rocks and Voltaic Key effects dropping it quickly and then you running cheap artifact creatures to sacrifice
Sasaya, Orochi Ascendant / Sasayas Essence Ive complained about setup costs being a tough hurdle for these cards up until now, but Sasaya, Orochi Ascendant has one thats both tough to meet and incredibly interesting
Big spells come down earlier, combos get easier to assemble, and if you have any untap synergies, things start getting silly fast
In Commander, you can only play one copy of each card in your decks (except for those whose text say otherwise, like Shadowborn Apostle and basic lands)
Return it to the battlefield under its owners control tapped and attacking at the beginning of that players next declare attackers step