Cards in the Main deck are always face-down, unless stated otherwise Face-down cards in the Extra Deck can be looked at by their possessor at any time, but cannot be looked at by their opponent.
Entomb is objectively better, since its cheaper and does more
Each turn, you can tap Vannifar and sacrifice another creature to tutor a creature from your deck that costs one more mana directly into play
Right now the most expensive Magic: The Gathering card in our price guide is Black Lotus, at a market price of $29,097.53
Agatha's Soul Cauldron + The Destined White Mage + Triskelion Now it's the turn of Agatha's Soul Cauldron, which is not meant to combo with MTG 's Vivi Ornitier, but rather, with The Destined White Mage, which is also from Final Fantasy
Do your homework, playtest accordingly, and make thoughtful decisions, ones derived from your own playtesting and experience