When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) {T}: Add {G}, {W}, or {U}.

Hexproof At the beginning of your upkeep, you may reveal your hand. If you do, you win the game if you own a card named Hedron Alignment in exile, in your hand, in your graveyard, and on the battlefield. {1}{U}: Scry 1.

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.) Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

({T}: Add {G} or {U}.) As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

If Gemstone Caverns is in your opening hand and you're not the starting player, you may begin the game with Gemstone Caverns on the battlefield with a luck counter on it. If you do, exile a card from your hand. {T}: Add {C}. If Gemstone Caverns has a luck counter on it, instead add one mana of any color.

({T}: Add {W} or {U}.) As Hallowed Fountain enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

({T}: Add {G} or {W}.) As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Tolaria West enters the battlefield tapped. {T}: Add {U}. Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with mana value 0, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Surveil 5. (Look at the top five cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)