Crypt Champion

Double strike
When Crypt Champion enters, each player puts a creature card with mana value 3 or less from their graveyard onto the battlefield.
When Crypt Champion enters, sacrifice it unless {R} was spent to cast it.

The List

RNA Guild Kit

Double strike
When Crypt Champion enters the battlefield, each player puts a creature card with converted mana cost 3 or less from their graveyard onto the battlefield.
When Crypt Champion enters the battlefield, sacrifice it unless {R} was spent to cast it.

Dissension

Double strike
When Crypt Champion comes into play, each player puts a creature card with converted mana cost 3 or less from his or her graveyard into play.
When Crypt Champion comes into play, sacrifice it unless {R} was spent to play it.

If this enters in a way other than announcing it as a spell, then the appropriate mana can't have been paid, and you'll have to sacrifice it.

The first triggered ability isn't targeted, so the creature cards aren't chosen until the ability resolves. Each player chooses which creature card from their own graveyard to return. If a player doesn't have an applicable creature card, that player does nothing. If a player does have any applicable cards, that player must return one to the battlefield.