When you select the deck in the challenge, it would have a statement saying so if that is the case
Down inside they go until they reach a door, for which a servant produces a pink crystal that Vito places inside an appropriate cavity
This red instant is definitely an odd one: Fight spells are rather rare in red, but the double utility (removal plus ritual), on top of conserving your red mana for the whole turn, has made The Last Agni Kai very popular in casual Commander, and good enough to see cEDH play in Dargo, the Shipwrecker decks (usually with Tymna the Weaver as partner commander)
You don't need the devotion that badly and they are just a bit awkward and low powered
If you do, that creature gains first strike until end of turn and must be blocked this turn if able
You really need to have a good idea of whats common enough in the format to deserve a slot in your deck, though, and occasionally these cards will still be a dead draw