Finale of Revelation requires 12+ mana to get all its perks, but that includes untapping some of your lands, shuffling your graveyard into your library, and removing your maximum hand size for the rest of the game
Kros has a unique take on the shield counter mechanic, as he can grant them to other monsters, while also giving them goad and trample, making them attack another player
We dont even know what itll be called yet
Pool of Vigorous Growth has the same ability, released in Jumpstart on MTG Arena
Since commander tax is an additional cost, it doesnt affect your commanders mana value
Once you get into the wider use items like dice, bags, though, you should start looking at the 2- and 4-star reviews instead of the 1- or 5-star ones, as they tend to be from actual users