All you need is to have your Commander on the field and you can cast this instantly, for free
Cards such as Paper Tiger, Rock Lobster, and Scissors Lizard may technically all be playable in Eternal formats
At least for a casual power level, the important questions I think we should ask are which themes play well together, which themes are well supported and which themes fit best into a viable Commander gameplan. For the first answer, it feels like there are two sets of synergistic themes that happen to align neatly with the two blocks of rules text
In the past Magic has released several different supplemental sets that added brand-new types of cards to the game, such as Vanguards, Schemes, Planes, and Phenomena
however, as suspected, Nykthos is very important to the overall game plan of the deck
Cards like Savage Ventmaw (plus a mana dork), Grand Warlord Radha, or a ton of mana dorks convert this into easy infinite extra combats