Despite the new contenders, it seems like Grolnok, the Omnivore remains by far the best fit for Omnibian
Many players, especially ones newer to the Commander format, will have a preconstructed deck, maybe with a few cards swapped, as their Commander deck
One Copy: Cards with narrow use, but your deck should have a way to search for the card if needed
And yes, I am incredibly excited at the long-overdue reprinting of the multiplayer allied color lands originally from Battlebond : And also, the much-needed reprint of Reflecting Pool
Play proceeds from there, with each player generating ink, playing cards using that ink, taking other actions, and then passing the turn to the other player
At that point, it's handy to know how to build an MTG deck - hit us up in the Wargamer Discord if you need more advice